[3/3] drm/bridge: Add NWL MIPI DSI host controller support

Commit Message

Guido Günther July 24, 2019, 3:52 p.m. UTC

This adds initial support for the NWL MIPI DSI Host controller found on
i.MX8 SoCs.

It adds support for the i.MX8MQ but the same IP can be found on
e.g. the i.MX8QXP.

It has been tested on the Librem 5 devkit using mxsfb.

Signed-off-by: Guido Günther <[e-mail]>
Co-developed-by: Robert Chiras <[e-mail]>
---
 drivers/gpu/drm/bridge/Kconfig           |   2 +
 drivers/gpu/drm/bridge/Makefile          |   1 +
 drivers/gpu/drm/bridge/imx-nwl/Kconfig   |  15 +
 drivers/gpu/drm/bridge/imx-nwl/Makefile  |   2 +
 drivers/gpu/drm/bridge/imx-nwl/nwl-drv.c | 529 ++++++++++++++++
 drivers/gpu/drm/bridge/imx-nwl/nwl-drv.h |  72 +++
 drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.c | 745 +++++++++++++++++++++++
 drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.h | 111 ++++
 8 files changed, 1477 insertions(+)
 create mode 100644 drivers/gpu/drm/bridge/imx-nwl/Kconfig
 create mode 100644 drivers/gpu/drm/bridge/imx-nwl/Makefile
 create mode 100644 drivers/gpu/drm/bridge/imx-nwl/nwl-drv.c
 create mode 100644 drivers/gpu/drm/bridge/imx-nwl/nwl-drv.h
 create mode 100644 drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.c
 create mode 100644 drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.h

Comments

Sam Ravnborg July 26, 2019, 10:08 a.m. UTC | #1

Hi Guido.

Following some trivial comments.
As for the overall design I already commented on that in the binding.
(bridge versus display controller)
That it can work on top of mxsfb is a good indication that it is a
bridge but I just do not see the full picture.

In general the code looked clean and neat.

On Wed, Jul 24, 2019 at 05:52:26PM +0200, Guido Günther wrote:
> This adds initial support for the NWL MIPI DSI Host controller found on
> i.MX8 SoCs.
> 
> It adds support for the i.MX8MQ but the same IP can be found on
> e.g. the i.MX8QXP.
> 
> It has been tested on the Librem 5 devkit using mxsfb.

Looking at mxsfb I wonder hw this was done, as there seems to be no
bridge support in mxsfb. Using a patched version of mxsfb?


> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index 4934fcf5a6f8..904a9eb3a20a 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -16,4 +16,5 @@ obj-$(CONFIG_DRM_ANALOGIX_DP) += analogix/
>  obj-$(CONFIG_DRM_I2C_ADV7511) += adv7511/
>  obj-$(CONFIG_DRM_TI_SN65DSI86) += ti-sn65dsi86.o
>  obj-$(CONFIG_DRM_TI_TFP410) += ti-tfp410.o
> +obj-y += imx-nwl/
obj-$(ONFIG_DRM_IMX_NWL_DSI) += imx-nwl/?
So we do not visit the directory unless required.

> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/imx-nwl/Makefile
> @@ -0,0 +1,2 @@
> +imx-nwl-objs := nwl-drv.o nwl-dsi.o

The preferred syntax is
imx-nwl-y := nwl-drv.o nwl-dsi.o

See for example Makefile for mxsfb.

Consider to introduce
header-test-y += nwl-drv.h nwl-dsi.h

So we at build time check that the headers are self-contained.
(they include what they need).


> +
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_of.h>
> +#include <drm/drm_panel.h>
> +#include <drm/drm_print.h>
> +#include <drm/drm_probe_helper.h>
> +#include <linux/clk-provider.h>
> +#include <linux/clk.h>
> +#include <linux/component.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/irq.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/mfd/syscon/imx8mq-iomuxc-gpr.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_platform.h>
> +#include <linux/phy/phy.h>
> +#include <linux/regmap.h>
> +#include <linux/sys_soc.h>
> +#include <video/videomode.h>
> +
> +#include "nwl-drv.h"
> +#include "nwl-dsi.h"

The most typical order of include files are:

#include <linux/*>

#include <video/*>

#include <drm/*>

#include ""

With the empty lines in-between each block.
And sorted like is already done here.

This in general for all the files for this driver.

> +
> +static bool
> +imx_nwl_dsi_bridge_mode_fixup(struct drm_bridge *bridge,
> +			      const struct drm_display_mode *mode,
> +			      struct drm_display_mode *adjusted_mode)
> +{
> +	struct imx_nwl_dsi *dsi = bridge_to_dsi(bridge);
> +	struct device *dev = dsi->dev;
> +	union phy_configure_opts new_cfg;
> +	unsigned long phy_ref_rate;
> +	int ret;
> +
> +	ret = nwl_dsi_get_dphy_params(dsi, adjusted_mode, &new_cfg);
> +	if (ret < 0)
> +		return ret;
> +
> +	/*
> +	 * If hs clock is unchanged, we're all good - all parameters are
> +	 * derived from it atm.
> +	 */
> +	if (new_cfg.mipi_dphy.hs_clk_rate == dsi->phy_cfg.mipi_dphy.hs_clk_rate)
> +		return true;
> +
> +	phy_ref_rate = clk_get_rate(dsi->phy_ref_clk);
> +	DRM_DEV_DEBUG_DRIVER(dev, "PHY at ref rate: %lu\n", phy_ref_rate);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dsi->dev,
> +			      "Cannot setup PHY for mode: %ux%u @%d Hz\n",
> +			      adjusted_mode->hdisplay, adjusted_mode->vdisplay,
> +			      adjusted_mode->clock);
> +		DRM_DEV_ERROR(dsi->dev, "PHY ref clk: %lu, bit clk: %lu\n",
> +			      phy_ref_rate, new_cfg.mipi_dphy.hs_clk_rate);
> +	} else {
> +		/* Save the new desired phy config */
> +		memcpy(&dsi->phy_cfg, &new_cfg, sizeof(new_cfg));
> +	}
> +
> +	/* LCDIF + NWL needs active high sync */
> +	adjusted_mode->flags |= (DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
> +	adjusted_mode->flags &= ~(DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC);
> +
> +	drm_display_mode_to_videomode(adjusted_mode, &dsi->vm);

Hmm, the videomode is just another representation of data already
included in display_mode.
And, as a personal itch, I consider videomode as something that belongs
in the old fb drivers, and not drm drivers. But that may be me only.


	Sam

Fabio Estevam July 26, 2019, 8:01 p.m. UTC | #2

Hi Guido,

Thanks for your work on this driver!

On Wed, Jul 24, 2019 at 12:52 PM Guido Günther <[e-mail]> wrote:

> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/imx-nwl/Kconfig
> @@ -0,0 +1,15 @@
> +config DRM_IMX_NWL_DSI
> +       tristate "Support for Northwest Logic MIPI DSI Host controller"
> +       depends on DRM && (ARCH_MXC || ARCH_MULTIPLATFORM || COMPILE_TEST)


This IP could potentially be found on other SoCs, so no need to make
it depend on ARCH_MXC.

> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_of.h>
> +#include <drm/drm_panel.h>
> +#include <drm/drm_print.h>
> +#include <drm/drm_probe_helper.h>
> +#include <linux/clk-provider.h>
> +#include <linux/clk.h>
> +#include <linux/component.h>
> +#include <linux/gpio/consumer.h>

I did not find gpio AP used in this driver.

> +static void imx_nwl_dsi_set_clocks(struct imx_nwl_dsi *dsi, bool enable)

Better make it to return 'int' instead...

> +{
> +       struct device *dev = dsi->dev;
> +       const char *id;
> +       struct clk *clk;
> +       unsigned long new_rate, cur_rate;
> +       bool enabled;
> +       size_t i;
> +       int ret;
> +
> +       DRM_DEV_DEBUG_DRIVER(dev, "%sabling platform clocks",

Please remove the letter 's' from 'sabling'.

> +                            enable ? "en" : "dis");
> +                       ret = clk_prepare_enable(clk);
> +                       if (ret < 0) {
> +                               DRM_DEV_ERROR(dev, "Failed to enable clock %s",
> +                                             id);

and propagate the error in case of clk_prepare_enable() failure.

> +                       }
> +                       dsi->clk_config[i].enabled = true;
> +                       cur_rate = clk_get_rate(clk);
> +                       DRM_DEV_DEBUG_DRIVER(
> +                               dev, "Enabled %s clk (rate: req=%lu act=%lu)\n",
> +                               id, new_rate, cur_rate);
> +               } else if (enabled) {
> +                       clk_disable_unprepare(clk);
> +                       dsi->clk_config[i].enabled = false;
> +                       DRM_DEV_DEBUG_DRIVER(dev, "Disabled %s clk\n", id);
> +               }
> +       }
> +}
> +
> +static void imx_nwl_dsi_enable(struct imx_nwl_dsi *dsi)

Same here. Please return 'int' instead.

> +{
> +       struct device *dev = dsi->dev;
> +       int ret;
> +
> +       imx_nwl_dsi_set_clocks(dsi, true);
> +
> +       ret = dsi->pdata->poweron(dsi);
> +       if (ret < 0)
> +               DRM_DEV_ERROR(dev, "Failed to power on DSI (%d)\n", ret);

If the power domain failed to turn on, it is better to propagate the error.

> +       phy_ref_rate = clk_get_rate(dsi->phy_ref_clk);
> +       DRM_DEV_DEBUG_DRIVER(dev, "PHY at ref rate: %lu\n", phy_ref_rate);
> +       if (ret < 0) {

This check looks wrong. At this point ret is always 0.

> +               DRM_DEV_ERROR(dsi->dev,
> +                             "Cannot setup PHY for mode: %ux%u @%d Hz\n",
> +                             adjusted_mode->hdisplay, adjusted_mode->vdisplay,
> +                             adjusted_mode->clock);
> +               DRM_DEV_ERROR(dsi->dev, "PHY ref clk: %lu, bit clk: %lu\n",
> +                             phy_ref_rate, new_cfg.mipi_dphy.hs_clk_rate);
> +       } else {
> +               /* Save the new desired phy config */
> +               memcpy(&dsi->phy_cfg, &new_cfg, sizeof(new_cfg));
> +       }
> +
> +       /* LCDIF + NWL needs active high sync */

Would this still work if DCSS is used instead?

> +       adjusted_mode->flags |= (DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
> +       adjusted_mode->flags &= ~(DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC);
> +
> +       drm_display_mode_to_videomode(adjusted_mode, &dsi->vm);
> +       drm_mode_debug_printmodeline(adjusted_mode);
> +
> +       return ret == 0;

At this point ret is always 0.

> +static void imx_nwl_dsi_bridge_pre_enable(struct drm_bridge *bridge)
> +{
> +       struct imx_nwl_dsi *dsi = bridge_to_dsi(bridge);
> +
> +       if (dsi->dpms_mode == DRM_MODE_DPMS_ON)
> +               return;
> +
> +       imx_nwl_select_input_source(dsi);

This function is i.MX8M specific, so better protect it to run only for
the i.MX8M variant.

> +       pm_runtime_get_sync(dsi->dev);
> +       imx_nwl_dsi_enable(dsi);
> +       nwl_dsi_enable(dsi);

Please check the error and propagate in the case of failure.

> +       dsi->dpms_mode = DRM_MODE_DPMS_ON;
> +}
> +

> +       dsi->csr = syscon_regmap_lookup_by_phandle(np, "csr");
> +       if (IS_ERR(dsi->csr) && dsi->pdata->ext_regs & IMX_REG_CSR) {
> +               ret = PTR_ERR(dsi->csr);
> +               DRM_DEV_ERROR(dsi->dev, "Failed to get CSR regmap: %d\n",

In this function (and globally in the driver) there is a mix of
DRM_DEV_ERROR() and dev_err().

Can we just pick one of the two and use it consistently?

Not sure what is the norm in drm code, but IMHO dev_err() looks prettier :-)

> +
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       base = devm_ioremap_resource(dsi->dev, res);

Could use devm_platform_ioremap_resource(), which makes it simpler.

> +err_cleanup:
> +       devm_free_irq(dev, dsi->irq, dsi);

No need to call devm_free_irq() here. The devm functions do not need
to be freed on probe.

> diff --git a/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.c b/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.c
> new file mode 100644
> index 000000000000..0e1463af162f
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.c
> @@ -0,0 +1,745 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * NWL DSI host driver
> + *
> + * Copyright (C) 2017 NXP
> + * Copyright (C) 2019 Purism SPC
> + */
> +
> +#include <asm/unaligned.h>

Is this asm header required?

> +/*
> + * DSI Video mode
> + */

Single line comment would suffice.

> +#define VIDEO_MODE_BURST_MODE_WITH_SYNC_PULSES         0
> +#define VIDEO_MODE_NON_BURST_MODE_WITH_SYNC_EVENTS     BIT(0)
> +#define VIDEO_MODE_BURST_MODE                          BIT(1)
> +
> +/*
> + * DPI color coding
> + */

Ditto.

> +#define DPI_16_BIT_565_PACKED  0
> +#define DPI_16_BIT_565_ALIGNED 1
> +#define DPI_16_BIT_565_SHIFTED 2
> +#define DPI_18_BIT_PACKED      3
> +#define DPI_18_BIT_ALIGNED     4
> +#define DPI_24_BIT             5
> +
> +/*
> + * DPI Pixel format
> + */

Ditto.

> +#define PIXEL_FORMAT_16  0
> +#define PIXEL_FORMAT_18  BIT(0)
> +#define PIXEL_FORMAT_18L BIT(1)
> +#define PIXEL_FORMAT_24  (BIT(0) | BIT(1))
> +
> +enum transfer_direction { DSI_PACKET_SEND, DSI_PACKET_RECEIVE };
> +
> +struct mipi_dsi_transfer {
> +       const struct mipi_dsi_msg *msg;
> +       struct mipi_dsi_packet packet;
> +       struct completion completed;
> +
> +       int status; /* status of transmission */
> +       enum transfer_direction direction;
> +       bool need_bta;
> +       u8 cmd;
> +       u16 rx_word_count;
> +       size_t tx_len; /* bytes sent */
> +       size_t rx_len; /* bytes received */
> +};

The comments here are kind of obvious, so I would just remove them.

> +static inline int nwl_dsi_write(struct imx_nwl_dsi *dsi, unsigned int reg,

inline can be dropped.

> +                               u32 val)
> +{
> +       int ret;
> +
> +       ret = regmap_write(dsi->regmap, reg, val);
> +       if (ret < 0)
> +               DRM_DEV_ERROR(dsi->dev,
> +                             "Failed to write NWL DSI reg 0x%x: %d\n", reg,
> +                             ret);
> +       return ret;
> +}
> +
> +static inline u32 nwl_dsi_read(struct imx_nwl_dsi *dsi, u32 reg)

Same here.

> +{
> +       unsigned int val;
> +       int ret;
> +
> +       ret = regmap_read(dsi->regmap, reg, &val);
> +       if (ret < 0)
> +               DRM_DEV_ERROR(dsi->dev, "Failed to read NWL DSI reg 0x%x: %d\n",
> +                             reg, ret);
> +
> +       return val;
> +}

It seems that we could simply use regmap_read/write() directly instead
of these functions.

> +int nwl_dsi_get_dphy_params(struct imx_nwl_dsi *dsi,
> +                           const struct drm_display_mode *mode,
> +                           union phy_configure_opts *phy_opts)
> +{
> +       unsigned long rate;
> +
> +       if (dsi->lanes < 1 || dsi->lanes > 4)
> +               return -EINVAL;
> +
> +       /*
> +        * So far the DPHY spec minimal timings work for both mixel
> +        * dphy and nwl dsi host
> +        */
> +       phy_mipi_dphy_get_default_config(
> +               mode->crtc_clock * 1000,
> +               mipi_dsi_pixel_format_to_bpp(dsi->format), dsi->lanes,
> +               &phy_opts->mipi_dphy);
> +       rate = clk_get_rate(dsi->tx_esc_clk);
> +       DRM_DEV_DEBUG_DRIVER(dsi->dev, "LP clk is @%lu Hz\n", rate);
> +       phy_opts->mipi_dphy.lp_clk_rate = rate;
> +
> +       return 0;
> +}
> +EXPORT_SYMBOL_GPL(nwl_dsi_get_dphy_params);

Does it really need to be exported? Why can't it be placed inside
nwl-drv.c and be made static?

> +/**

/* is enough


> + * ui2bc - UI time periods to byte clock cycles
> + */
> +static u32 ui2bc(struct imx_nwl_dsi *dsi, unsigned long long ui)
> +{
> +       int bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
> +
> +       return DIV_ROUND_UP(ui * dsi->lanes, dsi->vm.pixelclock * bpp);
> +}
> +
> +#define USEC_PER_SEC 1000000L

This definition already exists in include/linux/time64.h. No need to
redefine it.

> +static int nwl_dsi_enable_tx_clock(struct imx_nwl_dsi *dsi)
> +{
> +       struct device *dev = dsi->dev;
> +       int ret;
> +
> +       ret = clk_prepare_enable(dsi->tx_esc_clk);
> +       if (ret < 0) {
> +               DRM_DEV_ERROR(dev, "Failed to enable tx_esc clk: %d\n", ret);
> +               return ret;
> +       }
> +
> +       DRM_DEV_DEBUG_DRIVER(dev, "Enabled tx_esc clk @%lu Hz\n",
> +                            clk_get_rate(dsi->tx_esc_clk));
> +       return 0;
> +}

Do we really need this function? It looks like it would be simpler
just to call clk_prepare_enable() directly.

> +
> +static int nwl_dsi_enable_rx_clock(struct imx_nwl_dsi *dsi)
> +{
> +       struct device *dev = dsi->dev;
> +       int ret;
> +
> +       ret = clk_prepare_enable(dsi->rx_esc_clk);
> +       if (ret < 0) {
> +               DRM_DEV_ERROR(dev, "Failed to enable rx_esc clk: %d\n", ret);
> +               return ret;
> +       }
> +
> +       DRM_DEV_DEBUG_DRIVER(dev, "Enabled rx_esc clk @%lu Hz\n",
> +                            clk_get_rate(dsi->rx_esc_clk));
> +       return 0;
> +}

Same here.

> +static ssize_t nwl_dsi_host_transfer(struct mipi_dsi_host *dsi_host,
> +                                    const struct mipi_dsi_msg *msg)
> +{
> +       struct imx_nwl_dsi *dsi =
> +               container_of(dsi_host, struct imx_nwl_dsi, dsi_host);
> +       struct mipi_dsi_transfer xfer;
> +       ssize_t ret = 0;
> +
> +       /* Create packet to be sent */
> +       dsi->xfer = &xfer;
> +       ret = mipi_dsi_create_packet(&xfer.packet, msg);
> +       if (ret < 0) {
> +               dsi->xfer = NULL;
> +               return ret;
> +       }
> +
> +       if ((msg->type & MIPI_DSI_GENERIC_READ_REQUEST_0_PARAM ||
> +            msg->type & MIPI_DSI_GENERIC_READ_REQUEST_1_PARAM ||
> +            msg->type & MIPI_DSI_GENERIC_READ_REQUEST_2_PARAM ||
> +            msg->type & MIPI_DSI_DCS_READ) &&
> +           msg->rx_len > 0 && msg->rx_buf != NULL)
> +               xfer.direction = DSI_PACKET_RECEIVE;
> +       else
> +               xfer.direction = DSI_PACKET_SEND;
> +
> +       xfer.need_bta = (xfer.direction == DSI_PACKET_RECEIVE);
> +       xfer.need_bta |= (msg->flags & MIPI_DSI_MSG_REQ_ACK) ? 1 : 0;
> +       xfer.msg = msg;
> +       xfer.status = -ETIMEDOUT;
> +       xfer.rx_word_count = 0;
> +       xfer.rx_len = 0;
> +       xfer.cmd = 0x00;
> +       if (msg->tx_len > 0)
> +               xfer.cmd = ((u8 *)(msg->tx_buf))[0];
> +       init_completion(&xfer.completed);
> +
> +       nwl_dsi_enable_rx_clock(dsi);

This may fail, so better check the error.

ret = clk_prepare_enable()
if (ret < 0)
   return ret;

> +irqreturn_t nwl_dsi_irq_handler(int irq, void *data)
> +{
> +       u32 irq_status;
> +       struct imx_nwl_dsi *dsi = data;
> +
> +       irq_status = nwl_dsi_read(dsi, IRQ_STATUS);
> +
> +       if (irq_status & TX_PKT_DONE || irq_status & RX_PKT_HDR_RCVD ||
> +           irq_status & RX_PKT_PAYLOAD_DATA_RCVD)
> +               nwl_dsi_finish_transmission(dsi, irq_status);
> +
> +       return IRQ_HANDLED;
> +}
> +EXPORT_SYMBOL_GPL(nwl_dsi_irq_handler);

What about placing this function inside nwl-drv.c and make it static?

> +
> +int nwl_dsi_enable(struct imx_nwl_dsi *dsi)
> +{
> +       struct device *dev = dsi->dev;
> +       union phy_configure_opts *phy_cfg = &dsi->phy_cfg;
> +       int ret;
> +
> +       if (!dsi->lanes) {
> +               DRM_DEV_ERROR(dev, "Need DSI lanes: %d\n", dsi->lanes);
> +               return -EINVAL;
> +       }
> +
> +       ret = phy_init(dsi->phy);
> +       if (ret < 0) {
> +               DRM_DEV_ERROR(dev, "Failed to init DSI phy: %d\n", ret);
> +               return ret;
> +       }
> +
> +       ret = phy_configure(dsi->phy, phy_cfg);
> +       if (ret < 0) {
> +               DRM_DEV_ERROR(dev, "Failed to configure DSI phy: %d\n", ret);
> +               return ret;
> +       }
> +
> +       ret = nwl_dsi_enable_tx_clock(dsi);
> +       if (ret < 0) {
> +               DRM_DEV_ERROR(dev, "Failed to enable tx clock: %d\n", ret);
> +               return ret;
> +       }
> +
> +       ret = nwl_dsi_config_host(dsi);
> +       if (ret < 0) {
> +               DRM_DEV_ERROR(dev, "Failed to set up DSI: %d", ret);
> +               return ret;
> +       }
> +
> +       ret = nwl_dsi_config_dpi(dsi);
> +       if (ret < 0) {
> +               DRM_DEV_ERROR(dev, "Failed to set up DPI: %d", ret);
> +               return ret;
> +       }
> +
> +       ret = phy_power_on(dsi->phy);
> +       if (ret < 0) {
> +               DRM_DEV_ERROR(dev, "Failed to power on DPHY (%d)\n", ret);
> +               return ret;
> +       }
> +
> +       nwl_dsi_init_interrupts(dsi);
> +
> +       return 0;
> +}
> +EXPORT_SYMBOL_GPL(nwl_dsi_enable);

Same here.

> +
> +int nwl_dsi_disable(struct imx_nwl_dsi *dsi)
> +{
> +       struct device *dev = dsi->dev;
> +
> +       DRM_DEV_DEBUG_DRIVER(dev, "Disabling clocks and phy\n");
> +
> +       phy_power_off(dsi->phy);
> +       phy_exit(dsi->phy);
> +
> +       /* Disabling the clock before the phy breaks enabling dsi again */
> +       clk_disable_unprepare(dsi->tx_esc_clk);
> +
> +       return 0;
> +}
> +EXPORT_SYMBOL_GPL(nwl_dsi_disable);

Same here.

Laurent Pinchart July 27, 2019, 2:04 a.m. UTC | #3

Hello,

On Fri, Jul 26, 2019 at 05:01:52PM -0300, Fabio Estevam wrote:
> Hi Guido,
> 
> Thanks for your work on this driver!
> 
> On Wed, Jul 24, 2019 at 12:52 PM Guido Günther <[e-mail]> wrote:
> 
> > --- /dev/null
> > +++ b/drivers/gpu/drm/bridge/imx-nwl/Kconfig
> > @@ -0,0 +1,15 @@
> > +config DRM_IMX_NWL_DSI
> > +       tristate "Support for Northwest Logic MIPI DSI Host controller"
> > +       depends on DRM && (ARCH_MXC || ARCH_MULTIPLATFORM || COMPILE_TEST)
> 
> This IP could potentially be found on other SoCs, so no need to make
> it depend on ARCH_MXC.

I'd go even further and not use the prefix imx in the driver name or
anywhere in the code.

[snip]

Laurent Pinchart July 27, 2019, 2:47 a.m. UTC | #4

Hello Guido,

Thank you for the patch.

On Wed, Jul 24, 2019 at 05:52:26PM +0200, Guido Günther wrote:
> This adds initial support for the NWL MIPI DSI Host controller found on
> i.MX8 SoCs.
> 
> It adds support for the i.MX8MQ but the same IP can be found on
> e.g. the i.MX8QXP.
> 
> It has been tested on the Librem 5 devkit using mxsfb.
> 
> Signed-off-by: Guido Günther <[e-mail]>
> Co-developed-by: Robert Chiras <[e-mail]>
> ---
>  drivers/gpu/drm/bridge/Kconfig           |   2 +
>  drivers/gpu/drm/bridge/Makefile          |   1 +
>  drivers/gpu/drm/bridge/imx-nwl/Kconfig   |  15 +
>  drivers/gpu/drm/bridge/imx-nwl/Makefile  |   2 +
>  drivers/gpu/drm/bridge/imx-nwl/nwl-drv.c | 529 ++++++++++++++++
>  drivers/gpu/drm/bridge/imx-nwl/nwl-drv.h |  72 +++
>  drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.c | 745 +++++++++++++++++++++++
>  drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.h | 111 ++++
>  8 files changed, 1477 insertions(+)
>  create mode 100644 drivers/gpu/drm/bridge/imx-nwl/Kconfig
>  create mode 100644 drivers/gpu/drm/bridge/imx-nwl/Makefile
>  create mode 100644 drivers/gpu/drm/bridge/imx-nwl/nwl-drv.c
>  create mode 100644 drivers/gpu/drm/bridge/imx-nwl/nwl-drv.h
>  create mode 100644 drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.c
>  create mode 100644 drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.h
> 
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index a6eec908c43e..38c3145a7e57 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -152,6 +152,8 @@ source "drivers/gpu/drm/bridge/analogix/Kconfig"
>  
>  source "drivers/gpu/drm/bridge/adv7511/Kconfig"
>  
> +source "drivers/gpu/drm/bridge/imx-nwl/Kconfig"
> +

As this doesn't seem to be an i.MX-specific IP, I wouldn't use the name
imx in file names or in the code, at least in the parts that are not
NXP-specific.

>  source "drivers/gpu/drm/bridge/synopsys/Kconfig"
>  
>  endmenu
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index 4934fcf5a6f8..904a9eb3a20a 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -16,4 +16,5 @@ obj-$(CONFIG_DRM_ANALOGIX_DP) += analogix/
>  obj-$(CONFIG_DRM_I2C_ADV7511) += adv7511/
>  obj-$(CONFIG_DRM_TI_SN65DSI86) += ti-sn65dsi86.o
>  obj-$(CONFIG_DRM_TI_TFP410) += ti-tfp410.o
> +obj-y += imx-nwl/
>  obj-y += synopsys/
> diff --git a/drivers/gpu/drm/bridge/imx-nwl/Kconfig b/drivers/gpu/drm/bridge/imx-nwl/Kconfig
> new file mode 100644
> index 000000000000..822dba1b380a
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/imx-nwl/Kconfig
> @@ -0,0 +1,15 @@
> +config DRM_IMX_NWL_DSI
> +	tristate "Support for Northwest Logic MIPI DSI Host controller"
> +	depends on DRM && (ARCH_MXC || ARCH_MULTIPLATFORM || COMPILE_TEST)
> +	depends on COMMON_CLK
> +	depends on OF && HAS_IOMEM
> +	select DRM_KMS_HELPER
> +	select DRM_MIPI_DSI
> +	select DRM_PANEL_BRIDGE
> +	select GENERIC_PHY_MIPI_DPHY
> +	select MFD_SYSCON
> +	select REGMAP_MMIO
> +	help
> +	  This enables the Northwest Logic MIPI DSI Host controller as
> +	  found on NXP's i.MX8 Processors.
> +
> diff --git a/drivers/gpu/drm/bridge/imx-nwl/Makefile b/drivers/gpu/drm/bridge/imx-nwl/Makefile
> new file mode 100644
> index 000000000000..9fa63483da5b
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/imx-nwl/Makefile
> @@ -0,0 +1,2 @@
> +imx-nwl-objs := nwl-drv.o nwl-dsi.o
> +obj-$(CONFIG_DRM_IMX_NWL_DSI) += imx-nwl.o
> diff --git a/drivers/gpu/drm/bridge/imx-nwl/nwl-drv.c b/drivers/gpu/drm/bridge/imx-nwl/nwl-drv.c
> new file mode 100644
> index 000000000000..451f8f067c6f
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/imx-nwl/nwl-drv.c
> @@ -0,0 +1,529 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * i.MX8 NWL MIPI DSI host driver
> + *
> + * Copyright (C) 2017 NXP
> + * Copyright (C) 2019 Purism SPC
> + */
> +
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_of.h>
> +#include <drm/drm_panel.h>
> +#include <drm/drm_print.h>
> +#include <drm/drm_probe_helper.h>
> +#include <linux/clk-provider.h>

This doesn't seem to be needed.

> +#include <linux/clk.h>
> +#include <linux/component.h>

Same here.

> +#include <linux/gpio/consumer.h>
> +#include <linux/irq.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/mfd/syscon/imx8mq-iomuxc-gpr.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_platform.h>
> +#include <linux/phy/phy.h>
> +#include <linux/regmap.h>
> +#include <linux/sys_soc.h>
> +#include <video/videomode.h>
> +
> +#include "nwl-drv.h"
> +#include "nwl-dsi.h"
> +
> +#define DRV_NAME "imx-nwl-dsi"
> +
> +/* 8MQ SRC specific registers */
> +#define SRC_MIPIPHY_RCR	0x28
> +#define RESET_BYTE_N	BIT(1)
> +#define RESET_N		BIT(2)
> +#define DPI_RESET_N	BIT(3)
> +#define ESC_RESET_N	BIT(4)
> +#define PCLK_RESET_N	BIT(5)
> +
> +/* Possible clocks */
> +#define CLK_PIXEL	"pixel"
> +#define CLK_CORE	"core"
> +#define CLK_BYPASS	"bypass"
> +
> +enum imx_ext_regs {
> +	IMX_REG_CSR = BIT(1),
> +	IMX_REG_SRC = BIT(2),
> +	IMX_REG_GPR = BIT(3),
> +};
> +
> +static const struct regmap_config nwl_dsi_regmap_config = {
> +	.reg_bits = 16,
> +	.val_bits = 32,
> +	.reg_stride = 4,
> +	.max_register = IRQ_MASK2,
> +	.name = DRV_NAME,
> +};
> +
> +struct imx_nwl_platform_data {
> +	int (*poweron)(struct imx_nwl_dsi *dsi);
> +	int (*poweroff)(struct imx_nwl_dsi *dsi);
> +	u32 ext_regs; /* required external registers */
> +	struct imx_nwl_clk_config clk_config[NWL_MAX_PLATFORM_CLOCKS];
> +};
> +
> +static inline struct imx_nwl_dsi *bridge_to_dsi(struct drm_bridge *bridge)
> +{
> +	return container_of(bridge, struct imx_nwl_dsi, bridge);
> +}
> +
> +static void imx_nwl_dsi_set_clocks(struct imx_nwl_dsi *dsi, bool enable)
> +{
> +	struct device *dev = dsi->dev;
> +	const char *id;
> +	struct clk *clk;
> +	unsigned long new_rate, cur_rate;
> +	bool enabled;
> +	size_t i;
> +	int ret;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "%sabling platform clocks",
> +			     enable ? "en" : "dis");
> +	for (i = 0; i < ARRAY_SIZE(dsi->pdata->clk_config); i++) {
> +		if (!dsi->clk_config[i].present)
> +			continue;
> +		id = dsi->clk_config[i].id;
> +		clk = dsi->clk_config[i].clk;
> +		new_rate = dsi->clk_config[i].rate;
> +		cur_rate = clk_get_rate(clk);
> +		enabled = dsi->clk_config[i].enabled;
> +
> +		/* BYPASS clk must have the same rate as PHY_REF clk */
> +		if (!strcmp(id, CLK_BYPASS))
> +			new_rate = clk_get_rate(dsi->phy_ref_clk);
> +
> +		if (enable) {
> +			if (enabled && new_rate != cur_rate)
> +				clk_disable_unprepare(clk);
> +			else if (enabled && new_rate == cur_rate)
> +				continue;
> +			if (new_rate > 0)
> +				clk_set_rate(clk, new_rate);
> +			ret = clk_prepare_enable(clk);
> +			if (ret < 0) {
> +				DRM_DEV_ERROR(dev, "Failed to enable clock %s",
> +					      id);
> +			}
> +			dsi->clk_config[i].enabled = true;
> +			cur_rate = clk_get_rate(clk);
> +			DRM_DEV_DEBUG_DRIVER(
> +				dev, "Enabled %s clk (rate: req=%lu act=%lu)\n",
> +				id, new_rate, cur_rate);
> +		} else if (enabled) {
> +			clk_disable_unprepare(clk);
> +			dsi->clk_config[i].enabled = false;
> +			DRM_DEV_DEBUG_DRIVER(dev, "Disabled %s clk\n", id);
> +		}
> +	}
> +}
> +
> +static void imx_nwl_dsi_enable(struct imx_nwl_dsi *dsi)
> +{
> +	struct device *dev = dsi->dev;
> +	int ret;
> +
> +	imx_nwl_dsi_set_clocks(dsi, true);
> +
> +	ret = dsi->pdata->poweron(dsi);
> +	if (ret < 0)
> +		DRM_DEV_ERROR(dev, "Failed to power on DSI (%d)\n", ret);
> +}
> +
> +static void imx_nwl_dsi_disable(struct imx_nwl_dsi *dsi)
> +{
> +	struct device *dev = dsi->dev;
> +
> +	if (dsi->dpms_mode != DRM_MODE_DPMS_ON)
> +		return;
> +

The DRM core should guarantee that the bridge won't be disabled twice,
so I don't think you need this check. Similarly I think the enabled flag
in the imx_nwl_clk_config structure can be removed.

> +	DRM_DEV_DEBUG_DRIVER(dev, "Disabling encoder");

Is this really needed ?

> +	dsi->pdata->poweroff(dsi);
> +	imx_nwl_dsi_set_clocks(dsi, false);
> +}
> +
> +static void imx_nwl_select_input_source(struct imx_nwl_dsi *dsi)
> +{
> +	struct device_node *remote;
> +	u32 mux_val = IMX8MQ_GPR13_MIPI_MUX_SEL;
> +
> +	remote = of_graph_get_remote_node(dsi->dev->of_node, 0, 0);
> +	if (strcmp(remote->name, "lcdif") == 0)
> +		mux_val = 0;
> +

Can't you check the remote node at probe time instead of every time the
bridge gets enabled, and program the IO mux accordingly there ?

This code is i.MX-specific, so it should be isolated in an operation in
struct imx_nwl_platform_data.

> +	DRM_DEV_INFO(dsi->dev, "Using %s as input source\n",
> +		     (mux_val) ? "DCSS" : "LCDIF");
> +	regmap_update_bits(dsi->mux_sel, IOMUXC_GPR13,
> +			   IMX8MQ_GPR13_MIPI_MUX_SEL, mux_val);
> +	of_node_put(remote);
> +}
> +
> +static void imx_nwl_dsi_bridge_disable(struct drm_bridge *bridge)
> +{
> +	struct imx_nwl_dsi *dsi = bridge_to_dsi(bridge);
> +
> +	if (dsi->dpms_mode != DRM_MODE_DPMS_ON)
> +		return;
> +
> +	nwl_dsi_disable(dsi);
> +	imx_nwl_dsi_disable(dsi);
> +	pm_runtime_put_sync(dsi->dev);

Do you need a put_sync, wouldn't a put do ?

> +	dsi->dpms_mode = DRM_MODE_DPMS_OFF;
> +}
> +
> +static bool
> +imx_nwl_dsi_bridge_mode_fixup(struct drm_bridge *bridge,
> +			      const struct drm_display_mode *mode,
> +			      struct drm_display_mode *adjusted_mode)
> +{
> +	struct imx_nwl_dsi *dsi = bridge_to_dsi(bridge);
> +	struct device *dev = dsi->dev;
> +	union phy_configure_opts new_cfg;
> +	unsigned long phy_ref_rate;
> +	int ret;
> +
> +	ret = nwl_dsi_get_dphy_params(dsi, adjusted_mode, &new_cfg);
> +	if (ret < 0)
> +		return ret;
> +
> +	/*
> +	 * If hs clock is unchanged, we're all good - all parameters are
> +	 * derived from it atm.
> +	 */
> +	if (new_cfg.mipi_dphy.hs_clk_rate == dsi->phy_cfg.mipi_dphy.hs_clk_rate)
> +		return true;
> +
> +	phy_ref_rate = clk_get_rate(dsi->phy_ref_clk);
> +	DRM_DEV_DEBUG_DRIVER(dev, "PHY at ref rate: %lu\n", phy_ref_rate);
> +	if (ret < 0) {

This can't happen. Or are you missing a function call before the check ?

> +		DRM_DEV_ERROR(dsi->dev,
> +			      "Cannot setup PHY for mode: %ux%u @%d Hz\n",
> +			      adjusted_mode->hdisplay, adjusted_mode->vdisplay,
> +			      adjusted_mode->clock);
> +		DRM_DEV_ERROR(dsi->dev, "PHY ref clk: %lu, bit clk: %lu\n",
> +			      phy_ref_rate, new_cfg.mipi_dphy.hs_clk_rate);
> +	} else {
> +		/* Save the new desired phy config */
> +		memcpy(&dsi->phy_cfg, &new_cfg, sizeof(new_cfg));

The mode_fixup operation shall not change the device state, it can be
called multiple times when trying modes.

> +	}
> +
> +	/* LCDIF + NWL needs active high sync */
> +	adjusted_mode->flags |= (DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
> +	adjusted_mode->flags &= ~(DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC);
> +
> +	drm_display_mode_to_videomode(adjusted_mode, &dsi->vm);
> +	drm_mode_debug_printmodeline(adjusted_mode);
> +
> +	return ret == 0;

	return 0;

> +}
> +
> +static enum drm_mode_status
> +imx_nwl_dsi_bridge_mode_valid(struct drm_bridge *bridge,
> +			      const struct drm_display_mode *mode)
> +{
> +	struct imx_nwl_dsi *dsi = bridge_to_dsi(bridge);
> +	int bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
> +
> +	if (bpp < 0) {
> +		DRM_DEV_ERROR(dsi->dev, "Invalid pixel format: %d\n",
> +			      dsi->format);
> +		return MODE_BAD;
> +	}

The format isn't part of the mode, so this doesn't belong here. You
should here instead check that the mode clock and other timing data
(especially the visible resolution) are within the range supported by
the device.

> +
> +	return MODE_OK;
> +}
> +
> +static void imx_nwl_dsi_bridge_pre_enable(struct drm_bridge *bridge)
> +{
> +	struct imx_nwl_dsi *dsi = bridge_to_dsi(bridge);
> +
> +	if (dsi->dpms_mode == DRM_MODE_DPMS_ON)
> +		return;
> +
> +	imx_nwl_select_input_source(dsi);
> +	pm_runtime_get_sync(dsi->dev);
> +	imx_nwl_dsi_enable(dsi);
> +	nwl_dsi_enable(dsi);
> +	dsi->dpms_mode = DRM_MODE_DPMS_ON;
> +}
> +
> +static int imx_nwl_dsi_bridge_attach(struct drm_bridge *bridge)
> +{
> +	struct imx_nwl_dsi *dsi = bridge->driver_private;
> +	struct drm_encoder *encoder = bridge->encoder;
> +
> +	if (!encoder) {
> +		DRM_DEV_ERROR(dsi->dev, "Parent encoder object not found\n");
> +		return -ENODEV;
> +	}

Can't this happen ?

> +
> +	/* Set the encoder type as caller does not know it */
> +	bridge->encoder->encoder_type = DRM_MODE_ENCODER_DSI;

The encoder type is quite meaningless and userspace should not depend on
it, so I wouldn't set it here, especially that the encoder may not
expect the bridge to override its type.

> +
> +	/* Attach the panel-bridge to the dsi bridge */
> +	return drm_bridge_attach(bridge->encoder, dsi->panel_bridge, bridge);
> +}
> +
> +static void imx_nwl_dsi_bridge_detach(struct drm_bridge *bridge)
> +{
> +	struct imx_nwl_dsi *dsi = bridge->driver_private;
> +
> +	drm_of_panel_bridge_remove(dsi->dev->of_node, 1, 0);

This is already done in nwl_dsi_host_detach().

> +}
> +
> +/* see dw-mipi-dsi.c */

What for ? :-)

> +static const struct drm_bridge_funcs imx_nwl_dsi_bridge_funcs = {
> +	.pre_enable	= imx_nwl_dsi_bridge_pre_enable,
> +	.disable    = imx_nwl_dsi_bridge_disable,
> +	.mode_fixup = imx_nwl_dsi_bridge_mode_fixup,
> +	.mode_valid = imx_nwl_dsi_bridge_mode_valid,
> +	.attach	    = imx_nwl_dsi_bridge_attach,
> +	.detach	    = imx_nwl_dsi_bridge_detach,
> +};
> +
> +static int imx_nwl_dsi_parse_dt(struct imx_nwl_dsi *dsi)
> +{
> +	struct device_node *np = dsi->dev->of_node;
> +	struct platform_device *pdev = to_platform_device(dsi->dev);
> +	struct resource *res;
> +	struct clk *clk;
> +	const char *clk_id;
> +	void __iomem *base;
> +	int i, ret;
> +
> +	dsi->phy = devm_phy_get(dsi->dev, "dphy");
> +	if (IS_ERR(dsi->phy)) {
> +		ret = PTR_ERR(dsi->phy);
> +		dev_err(dsi->dev, "Could not get PHY (%d)\n", ret);
> +		return ret;
> +	}
> +
> +	/* Platform dependent clocks */
> +	memcpy(dsi->clk_config, dsi->pdata->clk_config,
> +	       sizeof(dsi->pdata->clk_config));
> +
> +	for (i = 0; i < ARRAY_SIZE(dsi->pdata->clk_config); i++) {
> +		if (!dsi->clk_config[i].present)
> +			continue;
> +
> +		clk_id = dsi->clk_config[i].id;
> +		clk = devm_clk_get(dsi->dev, clk_id);
> +		if (IS_ERR(clk)) {
> +			ret = PTR_ERR(clk);
> +			dev_err(dsi->dev, "Failed to get %s clock (%d)\n",
> +				clk_id, ret);
> +			return ret;
> +		}
> +		DRM_DEV_DEBUG_DRIVER(dsi->dev, "Setup clk %s (rate: %lu)\n",
> +				     clk_id, clk_get_rate(clk));
> +		dsi->clk_config[i].clk = clk;
> +	}
> +
> +	/* DSI clocks */
> +	clk = devm_clk_get(dsi->dev, "phy_ref");
> +	if (IS_ERR(clk)) {
> +		ret = PTR_ERR(clk);
> +		dev_err(dsi->dev, "Failed to get phy_ref clock: %d\n", ret);
> +		return ret;
> +	}
> +	dsi->phy_ref_clk = clk;
> +
> +	clk = devm_clk_get(dsi->dev, "rx_esc");
> +	if (IS_ERR(clk)) {
> +		ret = PTR_ERR(clk);
> +		dev_err(dsi->dev, "Failed to get rx_esc clock: %d\n", ret);
> +		return ret;
> +	}
> +	dsi->rx_esc_clk = clk;
> +
> +	clk = devm_clk_get(dsi->dev, "tx_esc");
> +	if (IS_ERR(clk)) {
> +		ret = PTR_ERR(clk);
> +		dev_err(dsi->dev, "Failed to get tx_esc clock: %d\n", ret);
> +		return ret;
> +	}
> +	dsi->tx_esc_clk = clk;
> +
> +	dsi->csr = syscon_regmap_lookup_by_phandle(np, "csr");
> +	if (IS_ERR(dsi->csr) && dsi->pdata->ext_regs & IMX_REG_CSR) {
> +		ret = PTR_ERR(dsi->csr);
> +		DRM_DEV_ERROR(dsi->dev, "Failed to get CSR regmap: %d\n",
> +			      ret);
> +		return ret;
> +	}

This doesn't seem to be used anywhere.

> +	dsi->reset = syscon_regmap_lookup_by_phandle(np, "src");
> +	if (IS_ERR(dsi->reset) && (dsi->pdata->ext_regs & IMX_REG_SRC)) {
> +		ret = PTR_ERR(dsi->reset);
> +		DRM_DEV_ERROR(dsi->dev, "Failed to get SRC regmap: %d\n",
> +			      ret);
> +		return ret;
> +	}

Couldn't you model a reset controller in that syscon, and use the reset
controller API here ? It would allow moving the i.MX-specific power on
and off functions from this driver, making it more generic.

> +	dsi->mux_sel = syscon_regmap_lookup_by_phandle(np, "mux-sel");
> +	if (IS_ERR(dsi->mux_sel) && (dsi->pdata->ext_regs & IMX_REG_GPR)) {
> +		ret = PTR_ERR(dsi->mux_sel);
> +		DRM_DEV_ERROR(dsi->dev, "Failed to get GPR regmap: %d\n",
> +			      ret);
> +		return ret;
> +	}
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	base = devm_ioremap_resource(dsi->dev, res);

You can replace those two calls with devm_platform_ioremap_resource().

> +	if (IS_ERR(base))
> +		return PTR_ERR(base);
> +
> +	dsi->regmap =
> +		devm_regmap_init_mmio(dsi->dev, base, &nwl_dsi_regmap_config);
> +	if (IS_ERR(dsi->regmap)) {
> +		ret = PTR_ERR(dsi->regmap);
> +		DRM_DEV_ERROR(dsi->dev,
> +			      "Failed to create NWL DSI regmap: %d\n", ret);
> +		return ret;
> +	}
> +
> +	dsi->irq = platform_get_irq(pdev, 0);
> +	if (dsi->irq < 0) {
> +		DRM_DEV_ERROR(dsi->dev, "Failed to get device IRQ: %d\n",
> +			      dsi->irq);
> +		return dsi->irq;
> +	}
> +
> +	return 0;
> +}
> +
> +static int imx8mq_dsi_poweron(struct imx_nwl_dsi *dsi)
> +{
> +	/* otherwise the display stays blank */
> +	usleep_range(200, 300);
> +
> +	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, PCLK_RESET_N,
> +			   PCLK_RESET_N);
> +	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, ESC_RESET_N,
> +			   ESC_RESET_N);
> +	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, RESET_BYTE_N,
> +			   RESET_BYTE_N);
> +	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, DPI_RESET_N,
> +			   DPI_RESET_N);
> +
> +	return 0;
> +}
> +
> +static int imx8mq_dsi_poweroff(struct imx_nwl_dsi *dsi)
> +{
> +	if (USE_SRC_RESET_QUIRK(dsi->quirks))
> +		return 0;
> +
> +	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, PCLK_RESET_N, 0);
> +	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, ESC_RESET_N, 0);
> +	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, RESET_BYTE_N, 0);
> +	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, DPI_RESET_N, 0);
> +	return 0;
> +}
> +
> +static const struct drm_bridge_timings imx_nwl_timings = {
> +	.input_bus_flags = DRM_BUS_FLAG_DE_LOW,
> +};
> +
> +static struct imx_nwl_platform_data imx8mq_dev = {

This structure should be const, especially as it contains function
pointers.

> +	.poweron = &imx8mq_dsi_poweron,
> +	.poweroff = &imx8mq_dsi_poweroff,
> +	.clk_config = {
> +		{ .id = CLK_CORE,   .present = true },
> +		{ .id = CLK_PIXEL,  .present = false },
> +		{ .id = CLK_BYPASS, .present = false },
> +	},
> +	.ext_regs = IMX_REG_SRC | IMX_REG_GPR,
> +};
> +
> +static const struct of_device_id imx_nwl_dsi_dt_ids[] = {
> +	{ .compatible = "fsl,imx8mq-nwl-dsi", .data = &imx8mq_dev, },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, imx_nwl_dsi_dt_ids);
> +
> +static const struct soc_device_attribute imx_nwl_quirks_match[] = {
> +	{ .soc_id = "i.MX8MQ", .revision = "2.0",
> +	  .data = (void *)(E11418_HS_MODE_QUIRK | SRC_RESET_QUIRK) },
> +	{ /* sentinel. */ },
> +};
> +
> +static int imx_nwl_dsi_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	const struct of_device_id *of_id =
> +		of_match_device(imx_nwl_dsi_dt_ids, dev);
> +	const struct imx_nwl_platform_data *pdata = of_id->data;
> +	const struct soc_device_attribute *attr;
> +	struct imx_nwl_dsi *dsi;
> +	int ret;
> +
> +	dsi = devm_kzalloc(dev, sizeof(*dsi), GFP_KERNEL);
> +	if (!dsi)
> +		return -ENOMEM;
> +
> +	dsi->dev = dev;
> +	dsi->pdata = pdata;
> +	dsi->dpms_mode = DRM_MODE_DPMS_OFF;

DPMS is legacy, let's not use it within the driver.

> +
> +	ret = imx_nwl_dsi_parse_dt(dsi);
> +	if (ret)
> +		return ret;
> +
> +	ret = devm_request_irq(dev, dsi->irq, nwl_dsi_irq_handler, 0,
> +			       dev_name(dev), dsi);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to request IRQ: %d (%d)\n", dsi->irq,
> +			      ret);
> +		return ret;
> +	}
> +
> +	dsi->dsi_host.ops = &nwl_dsi_host_ops;
> +	dsi->dsi_host.dev = dev;
> +	ret = mipi_dsi_host_register(&dsi->dsi_host);
> +	if (ret) {
> +		DRM_DEV_ERROR(dev, "Failed to register MIPI host: %d\n", ret);
> +		goto err_cleanup;
> +	}
> +
> +	attr = soc_device_match(imx_nwl_quirks_match);
> +	if (attr)
> +		dsi->quirks = (uintptr_t)attr->data;
> +
> +	dsi->bridge.driver_private = dsi;
> +	dsi->bridge.funcs = &imx_nwl_dsi_bridge_funcs;
> +	dsi->bridge.of_node = dev->of_node;
> +	dsi->bridge.timings = &imx_nwl_timings;
> +
> +	drm_bridge_add(&dsi->bridge);
> +
> +	dev_set_drvdata(dev, dsi);
> +	pm_runtime_enable(dev);
> +	return 0;
> +
> +err_cleanup:
> +	devm_free_irq(dev, dsi->irq, dsi);
> +	return ret;
> +}
> +
> +static int imx_nwl_dsi_remove(struct platform_device *pdev)
> +{
> +	pm_runtime_disable(&pdev->dev);

You should call drm_bridge_remove() here, not in nwl_dsi_host_detach().

> +	return 0;
> +}
> +
> +static struct platform_driver imx_nwl_dsi_driver = {
> +	.probe		= imx_nwl_dsi_probe,
> +	.remove		= imx_nwl_dsi_remove,
> +	.driver		= {
> +		.of_match_table = imx_nwl_dsi_dt_ids,
> +		.name	= DRV_NAME,
> +	},
> +};
> +
> +module_platform_driver(imx_nwl_dsi_driver);
> +
> +MODULE_AUTHOR("NXP Semiconductor");
> +MODULE_AUTHOR("Purism SPC");
> +MODULE_DESCRIPTION("i.MX8 Northwest Logic MIPI-DSI driver");
> +MODULE_LICENSE("GPL"); /* GPLv2 or later */
> diff --git a/drivers/gpu/drm/bridge/imx-nwl/nwl-drv.h b/drivers/gpu/drm/bridge/imx-nwl/nwl-drv.h
> new file mode 100644
> index 000000000000..a1e30c58b627
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/imx-nwl/nwl-drv.h
> @@ -0,0 +1,72 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * i.MX8 NWL MIPI DSI host driver
> + *
> + * Copyright (C) 2017 NXP
> + * Copyright (C) 2019 Purism SPC
> + */
> +
> +#ifndef __NWL_DRV_H__
> +#define __NWL_DRV_H__
> +
> +#include <drm/drm_mipi_dsi.h>
> +#include <linux/phy/phy.h>
> +
> +struct imx_nwl_platform_data;
> +
> +/* i.MX8 NWL quirks */
> +/* i.MX8MQ errata E11418 */
> +#define E11418_HS_MODE_QUIRK	    BIT(0)
> +#define USE_E11418_HS_MODE_QUIRK(x) ((x) & E11418_HS_MODE_QUIRK)
> +
> +/* Skip DSI bits in SRC on disable to avoid blank display on enable */
> +#define SRC_RESET_QUIRK		    BIT(1)
> +#define USE_SRC_RESET_QUIRK(x)	    ((x) & SRC_RESET_QUIRK)

The USE_* macros are not shorter to type, so I would type out the &
check explicitly.

> +
> +#define NWL_MAX_PLATFORM_CLOCKS 3
> +struct imx_nwl_clk_config {
> +	const char *id;
> +	struct clk *clk;
> +	bool present;
> +	bool enabled;
> +	u32 rate;
> +};
> +
> +struct imx_nwl_dsi {
> +	struct drm_bridge bridge;
> +	struct mipi_dsi_host dsi_host;
> +	struct drm_bridge *panel_bridge;
> +	struct device *dev;
> +	struct phy *phy;
> +	union phy_configure_opts phy_cfg;
> +	unsigned int quirks;
> +
> +	struct regmap *regmap;
> +	int irq;
> +
> +	/* External registers */
> +	struct regmap *csr;
> +	struct regmap *mux_sel;
> +	struct regmap *reset;
> +
> +	/* Platform dependent clocks */
> +	struct imx_nwl_clk_config clk_config[3];

I would use NWL_MAX_PLATFORM_CLOCKS instead of 3 as
imx_nwl_platform_data uses the macro.

> +	/* DSI clocks */
> +	struct clk *phy_ref_clk;
> +	struct clk *rx_esc_clk;
> +	struct clk *tx_esc_clk;
> +
> +	/* dsi lanes */
> +	u32 lanes;
> +	enum mipi_dsi_pixel_format format;
> +	struct videomode vm;
> +	unsigned long dsi_mode_flags;
> +
> +	int dpms_mode;
> +
> +	struct mipi_dsi_transfer *xfer;
> +
> +	const struct imx_nwl_platform_data *pdata;
> +};
> +
> +#endif /* __NWL_DRV_H__ */
> diff --git a/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.c b/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.c
> new file mode 100644
> index 000000000000..0e1463af162f
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.c
> @@ -0,0 +1,745 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * NWL DSI host driver
> + *
> + * Copyright (C) 2017 NXP
> + * Copyright (C) 2019 Purism SPC
> + */
> +
> +#include <asm/unaligned.h>
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_crtc_helper.h>
> +#include <drm/drm_of.h>
> +#include <drm/drm_panel.h>
> +#include <drm/drm_print.h>
> +#include <linux/clk.h>
> +#include <linux/irq.h>
> +#include <linux/regmap.h>
> +#include <video/mipi_display.h>
> +#include <video/videomode.h>
> +
> +#include "nwl-drv.h"
> +#include "nwl-dsi.h"
> +
> +#define MIPI_FIFO_TIMEOUT msecs_to_jiffies(500)
> +
> +/* PKT reg bit manipulation */
> +#define REG_MASK(e, s) (((1 << ((e) - (s) + 1)) - 1) << (s))
> +#define REG_PUT(x, e, s) (((x) << (s)) & REG_MASK(e, s))
> +#define REG_GET(x, e, s) (((x) & REG_MASK(e, s)) >> (s))

Let's not reinvent the wheel, linux/bits.h and linux/bitfield.h can be
used instead.

> +
> +/*
> + * PKT_CONTROL format:
> + * [15: 0] - word count
> + * [17:16] - virtual channel
> + * [23:18] - data type
> + * [24]	   - LP or HS select (0 - LP, 1 - HS)
> + * [25]	   - perform BTA after packet is sent
> + * [26]	   - perform BTA only, no packet tx
> + */
> +#define WC(x)		REG_PUT((x), 15,  0)
> +#define TX_VC(x)	REG_PUT((x), 17, 16)
> +#define TX_DT(x)	REG_PUT((x), 23, 18)
> +#define HS_SEL(x)	REG_PUT((x), 24, 24)
> +#define BTA_TX(x)	REG_PUT((x), 25, 25)
> +#define BTA_NO_TX(x)	REG_PUT((x), 26, 26)
> +
> +/*
> + * RX_PKT_HEADER format:
> + * [15: 0] - word count
> + * [21:16] - data type
> + * [23:22] - virtual channel
> + */
> +#define RX_DT(x) REG_GET((x), 21, 16)
> +#define RX_VC(x) REG_GET((x), 23, 22)
> +
> +/*
> + * DSI Video mode
> + */
> +#define VIDEO_MODE_BURST_MODE_WITH_SYNC_PULSES		0
> +#define VIDEO_MODE_NON_BURST_MODE_WITH_SYNC_EVENTS	BIT(0)
> +#define VIDEO_MODE_BURST_MODE				BIT(1)
> +
> +/*
> + * DPI color coding
> + */
> +#define DPI_16_BIT_565_PACKED	0
> +#define DPI_16_BIT_565_ALIGNED	1
> +#define DPI_16_BIT_565_SHIFTED	2
> +#define DPI_18_BIT_PACKED	3
> +#define DPI_18_BIT_ALIGNED	4
> +#define DPI_24_BIT		5
> +
> +/*
> + * DPI Pixel format
> + */
> +#define PIXEL_FORMAT_16  0
> +#define PIXEL_FORMAT_18  BIT(0)
> +#define PIXEL_FORMAT_18L BIT(1)
> +#define PIXEL_FORMAT_24  (BIT(0) | BIT(1))
> +
> +enum transfer_direction { DSI_PACKET_SEND, DSI_PACKET_RECEIVE };

Line breaks please.

> +
> +struct mipi_dsi_transfer {

Let's not use such a generic name for a driver-specific structure. You
should name is nwl_dsi_transfer.

> +	const struct mipi_dsi_msg *msg;
> +	struct mipi_dsi_packet packet;
> +	struct completion completed;
> +
> +	int status; /* status of transmission */
> +	enum transfer_direction direction;
> +	bool need_bta;
> +	u8 cmd;
> +	u16 rx_word_count;
> +	size_t tx_len; /* bytes sent */
> +	size_t rx_len; /* bytes received */
> +};
> +
> +static inline int nwl_dsi_write(struct imx_nwl_dsi *dsi, unsigned int reg,
> +				u32 val)
> +{
> +	int ret;
> +
> +	ret = regmap_write(dsi->regmap, reg, val);
> +	if (ret < 0)
> +		DRM_DEV_ERROR(dsi->dev,
> +			      "Failed to write NWL DSI reg 0x%x: %d\n", reg,
> +			      ret);
> +	return ret;
> +}
> +
> +static inline u32 nwl_dsi_read(struct imx_nwl_dsi *dsi, u32 reg)
> +{
> +	unsigned int val;
> +	int ret;
> +
> +	ret = regmap_read(dsi->regmap, reg, &val);
> +	if (ret < 0)
> +		DRM_DEV_ERROR(dsi->dev, "Failed to read NWL DSI reg 0x%x: %d\n",
> +			      reg, ret);
> +
> +	return val;

You're loosing the error...

> +}
> +
> +static u32 nwl_dsi_get_dpi_pixel_format(enum mipi_dsi_pixel_format format)
> +{
> +	switch (format) {
> +	case MIPI_DSI_FMT_RGB565:
> +		return PIXEL_FORMAT_16;
> +	case MIPI_DSI_FMT_RGB666:
> +		return PIXEL_FORMAT_18L;
> +	case MIPI_DSI_FMT_RGB666_PACKED:
> +		return PIXEL_FORMAT_18;
> +	case MIPI_DSI_FMT_RGB888:
> +		return PIXEL_FORMAT_24;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +int nwl_dsi_get_dphy_params(struct imx_nwl_dsi *dsi,
> +			    const struct drm_display_mode *mode,
> +			    union phy_configure_opts *phy_opts)
> +{
> +	unsigned long rate;
> +
> +	if (dsi->lanes < 1 || dsi->lanes > 4)
> +		return -EINVAL;
> +
> +	/*
> +	 * So far the DPHY spec minimal timings work for both mixel
> +	 * dphy and nwl dsi host
> +	 */
> +	phy_mipi_dphy_get_default_config(
> +		mode->crtc_clock * 1000,
> +		mipi_dsi_pixel_format_to_bpp(dsi->format), dsi->lanes,
> +		&phy_opts->mipi_dphy);
> +	rate = clk_get_rate(dsi->tx_esc_clk);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "LP clk is @%lu Hz\n", rate);
> +	phy_opts->mipi_dphy.lp_clk_rate = rate;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(nwl_dsi_get_dphy_params);

No need to export symbols, those fubctions are only meant to be called
from within the same module.

> +
> +#define PSEC_PER_SEC 1000000000000LL
> +/*
> + * ps2bc - Picoseconds to byte clock cycles
> + */
> +static u32 ps2bc(struct imx_nwl_dsi *dsi, unsigned long long ps)
> +{
> +	int bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
> +
> +	return DIV_ROUND_UP(ps * dsi->vm.pixelclock * bpp,
> +			    dsi->lanes * 8 * PSEC_PER_SEC);
> +}
> +
> +/**
> + * ui2bc - UI time periods to byte clock cycles
> + */
> +static u32 ui2bc(struct imx_nwl_dsi *dsi, unsigned long long ui)
> +{
> +	int bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
> +
> +	return DIV_ROUND_UP(ui * dsi->lanes, dsi->vm.pixelclock * bpp);
> +}
> +
> +#define USEC_PER_SEC 1000000L
> +/*
> + * us2bc - micro seconds to lp clock cycles
> + */
> +static u32 us2lp(u32 lp_clk_rate, unsigned long us)
> +{
> +	return DIV_ROUND_UP(us * lp_clk_rate, USEC_PER_SEC);
> +}
> +
> +static int nwl_dsi_config_host(struct imx_nwl_dsi *dsi)
> +{
> +	u32 cycles;
> +	struct phy_configure_opts_mipi_dphy *cfg = &dsi->phy_cfg.mipi_dphy;
> +
> +	if (dsi->lanes < 1 || dsi->lanes > 4)
> +		return -EINVAL;
> +
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "DSI Lanes %d\n", dsi->lanes);
> +	nwl_dsi_write(dsi, CFG_NUM_LANES, dsi->lanes - 1);
> +
> +	if (dsi->dsi_mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS) {
> +		nwl_dsi_write(dsi, CFG_NONCONTINUOUS_CLK, 0x01);
> +		nwl_dsi_write(dsi, CFG_AUTOINSERT_EOTP, 0x01);
> +	} else {
> +		nwl_dsi_write(dsi, CFG_NONCONTINUOUS_CLK, 0x00);
> +		nwl_dsi_write(dsi, CFG_AUTOINSERT_EOTP, 0x00);
> +	}
> +
> +	/* values in byte clock cycles */
> +	cycles = ui2bc(dsi, cfg->clk_pre);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_t_pre: 0x%x\n", cycles);
> +	nwl_dsi_write(dsi, CFG_T_PRE, cycles);
> +	cycles = ps2bc(dsi, cfg->lpx + cfg->clk_prepare + cfg->clk_zero);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_tx_gap (pre): 0x%x\n", cycles);
> +	cycles += ui2bc(dsi, cfg->clk_pre);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_tx_gap: 0x%x\n", cycles);
> +	nwl_dsi_write(dsi, CFG_T_POST, cycles);
> +	cycles = ps2bc(dsi, cfg->hs_exit);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_tx_gap: 0x%x\n", cycles);
> +	nwl_dsi_write(dsi, CFG_TX_GAP, cycles);
> +
> +	nwl_dsi_write(dsi, CFG_EXTRA_CMDS_AFTER_EOTP, 0x01);
> +	nwl_dsi_write(dsi, CFG_HTX_TO_COUNT, 0x00);
> +	nwl_dsi_write(dsi, CFG_LRX_H_TO_COUNT, 0x00);
> +	nwl_dsi_write(dsi, CFG_BTA_H_TO_COUNT, 0x00);
> +	/* In LP clock cycles */
> +	cycles = us2lp(cfg->lp_clk_rate, cfg->wakeup);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_twakeup: 0x%x\n", cycles);
> +	nwl_dsi_write(dsi, CFG_TWAKEUP, cycles);
> +
> +	return 0;
> +}
> +
> +static int nwl_dsi_config_dpi(struct imx_nwl_dsi *dsi)
> +{
> +	struct videomode *vm = &dsi->vm;
> +	u32 color_format, mode;
> +	bool burst_mode;
> +
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "hfront_porch = %d\n", vm->hfront_porch);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "hback_porch = %d\n", vm->hback_porch);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "hsync_len = %d\n", vm->hsync_len);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "hactive = %d\n", vm->hactive);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "vfront_porch = %d\n", vm->vfront_porch);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "vback_porch = %d\n", vm->vback_porch);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "vsync_len = %d\n", vm->vsync_len);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "vactive = %d\n", vm->vactive);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "clock = %lu kHz\n",
> +			     vm->pixelclock / 1000);
> +
> +	color_format = nwl_dsi_get_dpi_pixel_format(dsi->format);
> +	if (color_format < 0) {
> +		DRM_DEV_ERROR(dsi->dev, "Invalid color format 0x%x\n",
> +			      dsi->format);
> +		return color_format;
> +	}
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "pixel fmt = %d\n", dsi->format);
> +
> +	nwl_dsi_write(dsi, INTERFACE_COLOR_CODING, DPI_24_BIT);
> +	nwl_dsi_write(dsi, PIXEL_FORMAT, color_format);
> +	/*
> +	 * Adjusting input polarity based on the video mode results in
> +	 * a black screen so always pick active low:
> +	 */
> +	nwl_dsi_write(dsi, VSYNC_POLARITY, VSYNC_POLARITY_ACTIVE_LOW);
> +	nwl_dsi_write(dsi, HSYNC_POLARITY, HSYNC_POLARITY_ACTIVE_LOW);
> +
> +	burst_mode = (dsi->dsi_mode_flags & MIPI_DSI_MODE_VIDEO_BURST) &&
> +		     !(dsi->dsi_mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE);
> +
> +	if (burst_mode) {
> +		nwl_dsi_write(dsi, VIDEO_MODE, VIDEO_MODE_BURST_MODE);
> +		nwl_dsi_write(dsi, PIXEL_FIFO_SEND_LEVEL, 256);
> +	} else {
> +		mode = ((dsi->dsi_mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE) ?
> +				VIDEO_MODE_BURST_MODE_WITH_SYNC_PULSES :
> +				VIDEO_MODE_NON_BURST_MODE_WITH_SYNC_EVENTS);
> +		nwl_dsi_write(dsi, VIDEO_MODE, mode);
> +		nwl_dsi_write(dsi, PIXEL_FIFO_SEND_LEVEL, vm->hactive);
> +	}
> +
> +	nwl_dsi_write(dsi, HFP, vm->hfront_porch);
> +	nwl_dsi_write(dsi, HBP, vm->hback_porch);
> +	nwl_dsi_write(dsi, HSA, vm->hsync_len);
> +
> +	nwl_dsi_write(dsi, ENABLE_MULT_PKTS, 0x0);
> +	nwl_dsi_write(dsi, BLLP_MODE, 0x1);
> +	nwl_dsi_write(dsi, ENABLE_MULT_PKTS, 0x0);
> +	nwl_dsi_write(dsi, USE_NULL_PKT_BLLP, 0x0);
> +	nwl_dsi_write(dsi, VC, 0x0);
> +
> +	nwl_dsi_write(dsi, PIXEL_PAYLOAD_SIZE, vm->hactive);
> +	nwl_dsi_write(dsi, VACTIVE, vm->vactive - 1);
> +	nwl_dsi_write(dsi, VBP, vm->vback_porch);
> +	nwl_dsi_write(dsi, VFP, vm->vfront_porch);
> +
> +	return 0;
> +}
> +
> +static int nwl_dsi_enable_tx_clock(struct imx_nwl_dsi *dsi)
> +{
> +	struct device *dev = dsi->dev;
> +	int ret;
> +
> +	ret = clk_prepare_enable(dsi->tx_esc_clk);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to enable tx_esc clk: %d\n", ret);
> +		return ret;
> +	}
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "Enabled tx_esc clk @%lu Hz\n",
> +			     clk_get_rate(dsi->tx_esc_clk));
> +	return 0;
> +}
> +
> +static int nwl_dsi_enable_rx_clock(struct imx_nwl_dsi *dsi)
> +{
> +	struct device *dev = dsi->dev;
> +	int ret;
> +
> +	ret = clk_prepare_enable(dsi->rx_esc_clk);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to enable rx_esc clk: %d\n", ret);
> +		return ret;
> +	}
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "Enabled rx_esc clk @%lu Hz\n",
> +			     clk_get_rate(dsi->rx_esc_clk));
> +	return 0;
> +}
> +
> +static void nwl_dsi_init_interrupts(struct imx_nwl_dsi *dsi)
> +{
> +	u32 irq_enable;
> +
> +	nwl_dsi_write(dsi, IRQ_MASK, 0xffffffff);
> +	nwl_dsi_write(dsi, IRQ_MASK2, 0x7);
> +
> +	irq_enable = ~(u32)(TX_PKT_DONE_MASK | RX_PKT_HDR_RCVD_MASK |
> +			    TX_FIFO_OVFLW_MASK | HS_TX_TIMEOUT_MASK);
> +
> +	nwl_dsi_write(dsi, IRQ_MASK, irq_enable);
> +}
> +
> +static int nwl_dsi_host_attach(struct mipi_dsi_host *dsi_host,
> +			       struct mipi_dsi_device *device)
> +{
> +	struct imx_nwl_dsi *dsi =
> +		container_of(dsi_host, struct imx_nwl_dsi, dsi_host);
> +	struct device *dev = dsi->dev;
> +	struct drm_bridge *bridge;
> +	struct drm_panel *panel;
> +	int ret;
> +
> +	DRM_DEV_INFO(dev, "lanes=%u, format=0x%x flags=0x%lx\n", device->lanes,
> +		     device->format, device->mode_flags);
> +
> +	if (device->lanes < 1 || device->lanes > 4)
> +		return -EINVAL;
> +
> +	dsi->lanes = device->lanes;
> +	dsi->format = device->format;
> +	dsi->dsi_mode_flags = device->mode_flags;
> +
> +	ret = drm_of_find_panel_or_bridge(dsi->dev->of_node, 1, 0, &panel,
> +					  &bridge);
> +	if (ret)
> +		return ret;
> +
> +	if (panel) {
> +		bridge = drm_panel_bridge_add(panel, DRM_MODE_CONNECTOR_DSI);
> +		if (IS_ERR(bridge))
> +			return PTR_ERR(bridge);
> +	}
> +
> +	dsi->panel_bridge = bridge;
> +	drm_bridge_add(&dsi->bridge);
> +
> +	return 0;
> +}
> +
> +static int nwl_dsi_host_detach(struct mipi_dsi_host *dsi_host,
> +			       struct mipi_dsi_device *device)
> +{
> +	struct imx_nwl_dsi *dsi =
> +		container_of(dsi_host, struct imx_nwl_dsi, dsi_host);
> +
> +	drm_of_panel_bridge_remove(dsi->dev->of_node, 1, 0);
> +	drm_bridge_remove(&dsi->bridge);
> +
> +	return 0;
> +}
> +
> +static bool nwl_dsi_read_packet(struct imx_nwl_dsi *dsi, u32 status)
> +{
> +	struct device *dev = dsi->dev;
> +	struct mipi_dsi_transfer *xfer = dsi->xfer;
> +	u8 *payload = xfer->msg->rx_buf;
> +	u32 val;
> +	u16 word_count;
> +	u8 channel;
> +	u8 data_type;
> +
> +	xfer->status = 0;
> +
> +	if (xfer->rx_word_count == 0) {
> +		if (!(status & RX_PKT_HDR_RCVD))
> +			return false;
> +		/* Get the RX header and parse it */
> +		val = nwl_dsi_read(dsi, RX_PKT_HEADER);
> +		word_count = WC(val);
> +		channel = RX_VC(val);
> +		data_type = RX_DT(val);
> +
> +		if (channel != xfer->msg->channel) {
> +			DRM_DEV_ERROR(dev,
> +				      "[%02X] Channel mismatch (%u != %u)\n",
> +				      xfer->cmd, channel, xfer->msg->channel);
> +			return true;
> +		}
> +
> +		switch (data_type) {
> +		case MIPI_DSI_RX_GENERIC_SHORT_READ_RESPONSE_2BYTE:
> +			/* Fall through */
> +		case MIPI_DSI_RX_DCS_SHORT_READ_RESPONSE_2BYTE:
> +			if (xfer->msg->rx_len > 1) {
> +				/* read second byte */
> +				payload[1] = word_count >> 8;
> +				++xfer->rx_len;
> +			}
> +			/* Fall through */
> +		case MIPI_DSI_RX_GENERIC_SHORT_READ_RESPONSE_1BYTE:
> +			/* Fall through */
> +		case MIPI_DSI_RX_DCS_SHORT_READ_RESPONSE_1BYTE:
> +			if (xfer->msg->rx_len > 0) {
> +				/* read first byte */
> +				payload[0] = word_count & 0xff;
> +				++xfer->rx_len;
> +			}
> +			xfer->status = xfer->rx_len;
> +			return true;
> +		case MIPI_DSI_RX_ACKNOWLEDGE_AND_ERROR_REPORT:
> +			word_count &= 0xff;
> +			DRM_DEV_ERROR(dev, "[%02X] DSI error report: 0x%02x\n",
> +				      xfer->cmd, word_count);
> +			xfer->status = -EPROTO;
> +			return true;
> +		}
> +
> +		if (word_count > xfer->msg->rx_len) {
> +			DRM_DEV_ERROR(
> +				dev,
> +				"[%02X] Receive buffer too small: %lu (< %u)\n",
> +				xfer->cmd, xfer->msg->rx_len, word_count);
> +			return true;
> +		}
> +
> +		xfer->rx_word_count = word_count;
> +	} else {
> +		/* Set word_count from previous header read */
> +		word_count = xfer->rx_word_count;
> +	}
> +
> +	/* If RX payload is not yet received, wait for it */
> +	if (!(status & RX_PKT_PAYLOAD_DATA_RCVD))
> +		return false;
> +
> +	/* Read the RX payload */
> +	while (word_count >= 4) {
> +		val = nwl_dsi_read(dsi, RX_PAYLOAD);
> +		payload[0] = (val >> 0) & 0xff;
> +		payload[1] = (val >> 8) & 0xff;
> +		payload[2] = (val >> 16) & 0xff;
> +		payload[3] = (val >> 24) & 0xff;
> +		payload += 4;
> +		xfer->rx_len += 4;
> +		word_count -= 4;
> +	}
> +
> +	if (word_count > 0) {
> +		val = nwl_dsi_read(dsi, RX_PAYLOAD);
> +		switch (word_count) {
> +		case 3:
> +			payload[2] = (val >> 16) & 0xff;
> +			++xfer->rx_len;
> +			/* Fall through */
> +		case 2:
> +			payload[1] = (val >> 8) & 0xff;
> +			++xfer->rx_len;
> +			/* Fall through */
> +		case 1:
> +			payload[0] = (val >> 0) & 0xff;
> +			++xfer->rx_len;
> +			break;
> +		}
> +	}
> +
> +	xfer->status = xfer->rx_len;
> +
> +	return true;
> +}
> +
> +static void nwl_dsi_finish_transmission(struct imx_nwl_dsi *dsi, u32 status)
> +{
> +	struct mipi_dsi_transfer *xfer = dsi->xfer;
> +	bool end_packet = false;
> +
> +	if (!xfer)
> +		return;
> +
> +	if (status & TX_FIFO_OVFLW) {
> +		DRM_DEV_ERROR_RATELIMITED(dsi->dev, "tx fifo overflow\n");
> +		return;
> +	}
> +
> +	if (status & HS_TX_TIMEOUT) {
> +		DRM_DEV_ERROR_RATELIMITED(dsi->dev, "HS tx timeout\n");
> +		return;
> +	}
> +
> +	if (xfer->direction == DSI_PACKET_SEND && status & TX_PKT_DONE) {
> +		xfer->status = xfer->tx_len;
> +		end_packet = true;
> +	} else if (status & DPHY_DIRECTION &&
> +		   ((status & (RX_PKT_HDR_RCVD | RX_PKT_PAYLOAD_DATA_RCVD)))) {
> +		end_packet = nwl_dsi_read_packet(dsi, status);
> +	}
> +
> +	if (end_packet)
> +		complete(&xfer->completed);
> +}
> +
> +static void nwl_dsi_begin_transmission(struct imx_nwl_dsi *dsi)
> +{
> +	struct mipi_dsi_transfer *xfer = dsi->xfer;
> +	struct mipi_dsi_packet *pkt = &xfer->packet;
> +	const u8 *payload;
> +	size_t length;
> +	u16 word_count;
> +	u8 hs_mode;
> +	u32 val;
> +	u32 hs_workaround = 0;
> +
> +	/* Send the payload, if any */
> +	length = pkt->payload_length;
> +	payload = pkt->payload;
> +
> +	while (length >= 4) {
> +		val = get_unaligned_le32(payload);

The framework doesn't guarantee the payload to be aligned on a multiple
of 4 bytes ?

> +		hs_workaround |= !(val & 0xFFFF00);
> +		nwl_dsi_write(dsi, TX_PAYLOAD, val);
> +		payload += 4;
> +		length -= 4;
> +	}
> +	/* Send the rest of the payload */
> +	val = 0;
> +	switch (length) {
> +	case 3:
> +		val |= payload[2] << 16;
> +		/* Fall through */
> +	case 2:
> +		val |= payload[1] << 8;
> +		hs_workaround |= !(val & 0xFFFF00);
> +		/* Fall through */
> +	case 1:
> +		val |= payload[0];
> +		nwl_dsi_write(dsi, TX_PAYLOAD, val);
> +		break;
> +	}
> +	xfer->tx_len = pkt->payload_length;
> +
> +	/*
> +	 * Send the header
> +	 * header[0] = Virtual Channel + Data Type
> +	 * header[1] = Word Count LSB (LP) or first param (SP)
> +	 * header[2] = Word Count MSB (LP) or second param (SP)
> +	 */
> +	word_count = pkt->header[1] | (pkt->header[2] << 8);
> +	if ((hs_workaround && USE_E11418_HS_MODE_QUIRK(dsi->quirks))) {
> +		DRM_DEV_DEBUG_DRIVER(dsi->dev,
> +				     "Using hs mode workaround for cmd 0x%x\n",
> +				     xfer->cmd);
> +		hs_mode = 1;
> +	} else {
> +		hs_mode = (xfer->msg->flags & MIPI_DSI_MSG_USE_LPM) ? 0 : 1;
> +	}
> +	val = WC(word_count) |
> +		TX_VC(xfer->msg->channel) |
> +		TX_DT(xfer->msg->type) |
> +		HS_SEL(hs_mode) |
> +		BTA_TX(xfer->need_bta);
> +	nwl_dsi_write(dsi, PKT_CONTROL, val);
> +
> +	/* Send packet command */
> +	nwl_dsi_write(dsi, SEND_PACKET, 0x1);
> +}
> +
> +static ssize_t nwl_dsi_host_transfer(struct mipi_dsi_host *dsi_host,
> +				     const struct mipi_dsi_msg *msg)
> +{
> +	struct imx_nwl_dsi *dsi =
> +		container_of(dsi_host, struct imx_nwl_dsi, dsi_host);
> +	struct mipi_dsi_transfer xfer;
> +	ssize_t ret = 0;
> +
> +	/* Create packet to be sent */
> +	dsi->xfer = &xfer;
> +	ret = mipi_dsi_create_packet(&xfer.packet, msg);
> +	if (ret < 0) {
> +		dsi->xfer = NULL;
> +		return ret;
> +	}
> +
> +	if ((msg->type & MIPI_DSI_GENERIC_READ_REQUEST_0_PARAM ||
> +	     msg->type & MIPI_DSI_GENERIC_READ_REQUEST_1_PARAM ||
> +	     msg->type & MIPI_DSI_GENERIC_READ_REQUEST_2_PARAM ||
> +	     msg->type & MIPI_DSI_DCS_READ) &&
> +	    msg->rx_len > 0 && msg->rx_buf != NULL)
> +		xfer.direction = DSI_PACKET_RECEIVE;
> +	else
> +		xfer.direction = DSI_PACKET_SEND;
> +
> +	xfer.need_bta = (xfer.direction == DSI_PACKET_RECEIVE);
> +	xfer.need_bta |= (msg->flags & MIPI_DSI_MSG_REQ_ACK) ? 1 : 0;
> +	xfer.msg = msg;
> +	xfer.status = -ETIMEDOUT;
> +	xfer.rx_word_count = 0;
> +	xfer.rx_len = 0;
> +	xfer.cmd = 0x00;
> +	if (msg->tx_len > 0)
> +		xfer.cmd = ((u8 *)(msg->tx_buf))[0];
> +	init_completion(&xfer.completed);
> +
> +	nwl_dsi_enable_rx_clock(dsi);
> +
> +	/* Initiate the DSI packet transmision */
> +	nwl_dsi_begin_transmission(dsi);
> +
> +	if (!wait_for_completion_timeout(&xfer.completed, MIPI_FIFO_TIMEOUT)) {
> +		DRM_DEV_ERROR(dsi_host->dev, "[%02X] DSI transfer timed out\n",
> +			      xfer.cmd);
> +		ret = -ETIMEDOUT;
> +	} else {
> +		ret = xfer.status;
> +	}
> +
> +	clk_disable_unprepare(dsi->rx_esc_clk);
> +
> +	return ret;
> +}
> +
> +const struct mipi_dsi_host_ops nwl_dsi_host_ops = {
> +	.attach = nwl_dsi_host_attach,
> +	.detach = nwl_dsi_host_detach,
> +	.transfer = nwl_dsi_host_transfer,
> +};
> +
> +irqreturn_t nwl_dsi_irq_handler(int irq, void *data)
> +{
> +	u32 irq_status;
> +	struct imx_nwl_dsi *dsi = data;
> +
> +	irq_status = nwl_dsi_read(dsi, IRQ_STATUS);
> +
> +	if (irq_status & TX_PKT_DONE || irq_status & RX_PKT_HDR_RCVD ||
> +	    irq_status & RX_PKT_PAYLOAD_DATA_RCVD)
> +		nwl_dsi_finish_transmission(dsi, irq_status);
> +
> +	return IRQ_HANDLED;
> +}
> +EXPORT_SYMBOL_GPL(nwl_dsi_irq_handler);
> +
> +int nwl_dsi_enable(struct imx_nwl_dsi *dsi)
> +{
> +	struct device *dev = dsi->dev;
> +	union phy_configure_opts *phy_cfg = &dsi->phy_cfg;
> +	int ret;
> +
> +	if (!dsi->lanes) {
> +		DRM_DEV_ERROR(dev, "Need DSI lanes: %d\n", dsi->lanes);
> +		return -EINVAL;
> +	}
> +
> +	ret = phy_init(dsi->phy);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to init DSI phy: %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = phy_configure(dsi->phy, phy_cfg);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to configure DSI phy: %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = nwl_dsi_enable_tx_clock(dsi);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to enable tx clock: %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = nwl_dsi_config_host(dsi);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to set up DSI: %d", ret);
> +		return ret;
> +	}
> +
> +	ret = nwl_dsi_config_dpi(dsi);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to set up DPI: %d", ret);
> +		return ret;
> +	}
> +
> +	ret = phy_power_on(dsi->phy);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to power on DPHY (%d)\n", ret);
> +		return ret;
> +	}
> +
> +	nwl_dsi_init_interrupts(dsi);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(nwl_dsi_enable);
> +
> +int nwl_dsi_disable(struct imx_nwl_dsi *dsi)
> +{
> +	struct device *dev = dsi->dev;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "Disabling clocks and phy\n");
> +
> +	phy_power_off(dsi->phy);
> +	phy_exit(dsi->phy);
> +
> +	/* Disabling the clock before the phy breaks enabling dsi again */
> +	clk_disable_unprepare(dsi->tx_esc_clk);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(nwl_dsi_disable);
> diff --git a/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.h b/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.h
> new file mode 100644
> index 000000000000..7bcf804843e2
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.h
> @@ -0,0 +1,111 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * i.MX8 NWL MIPI DSI host driver
> + *
> + * Copyright (C) 2017 NXP
> + * Copyright (C) 2019 Purism SPC
> + */
> +#ifndef __NWL_DSI_H__
> +#define __NWL_DSI_H__
> +
> +#include <drm/drm_mipi_dsi.h>
> +
> +/* DSI HOST registers */
> +#define CFG_NUM_LANES			0x0

Some of the register names are quite prone to namespace clashes. I
recommend prefixing them all with NWL_DSI_.

> +#define CFG_NONCONTINUOUS_CLK		0x4
> +#define CFG_T_PRE			0x8
> +#define CFG_T_POST			0xc
> +#define CFG_TX_GAP			0x10
> +#define CFG_AUTOINSERT_EOTP		0x14
> +#define CFG_EXTRA_CMDS_AFTER_EOTP	0x18
> +#define CFG_HTX_TO_COUNT		0x1c
> +#define CFG_LRX_H_TO_COUNT		0x20
> +#define CFG_BTA_H_TO_COUNT		0x24
> +#define CFG_TWAKEUP			0x28
> +#define CFG_STATUS_OUT			0x2c
> +#define RX_ERROR_STATUS			0x30
> +
> +/* DSI DPI registers */
> +#define PIXEL_PAYLOAD_SIZE		0x200
> +#define PIXEL_FIFO_SEND_LEVEL		0x204
> +#define INTERFACE_COLOR_CODING		0x208
> +#define PIXEL_FORMAT			0x20c
> +#define VSYNC_POLARITY			0x210
> +#define VSYNC_POLARITY_ACTIVE_LOW	0
> +#define VSYNC_POLARITY_ACTIVE_HIGH	BIT(1)
> +
> +#define HSYNC_POLARITY			0x214
> +#define HSYNC_POLARITY_ACTIVE_LOW	0
> +#define HSYNC_POLARITY_ACTIVE_HIGH	BIT(1)
> +
> +#define VIDEO_MODE			0x218
> +#define HFP				0x21c
> +#define HBP				0x220
> +#define HSA				0x224
> +#define ENABLE_MULT_PKTS		0x228
> +#define VBP				0x22c
> +#define VFP				0x230
> +#define BLLP_MODE			0x234
> +#define USE_NULL_PKT_BLLP		0x238
> +#define VACTIVE				0x23c
> +#define VC				0x240
> +
> +/* DSI APB PKT control */
> +#define TX_PAYLOAD			0x280
> +#define PKT_CONTROL			0x284
> +#define SEND_PACKET			0x288
> +#define PKT_STATUS			0x28c
> +#define PKT_FIFO_WR_LEVEL		0x290
> +#define PKT_FIFO_RD_LEVEL		0x294
> +#define RX_PAYLOAD			0x298
> +#define RX_PKT_HEADER			0x29c
> +
> +/* DSI IRQ handling */
> +#define IRQ_STATUS			0x2a0
> +#define SM_NOT_IDLE			BIT(0)
> +#define TX_PKT_DONE			BIT(1)
> +#define DPHY_DIRECTION			BIT(2)
> +#define TX_FIFO_OVFLW			BIT(3)
> +#define TX_FIFO_UDFLW			BIT(4)
> +#define RX_FIFO_OVFLW			BIT(5)
> +#define RX_FIFO_UDFLW			BIT(6)
> +#define RX_PKT_HDR_RCVD			BIT(7)
> +#define RX_PKT_PAYLOAD_DATA_RCVD	BIT(8)
> +#define BTA_TIMEOUT			BIT(29)
> +#define LP_RX_TIMEOUT			BIT(30)
> +#define HS_TX_TIMEOUT			BIT(31)
> +
> +#define IRQ_STATUS2			0x2a4
> +#define SINGLE_BIT_ECC_ERR		BIT(0)
> +#define MULTI_BIT_ECC_ERR		BIT(1)
> +#define CRC_ERR				BIT(2)
> +
> +#define IRQ_MASK			0x2a8
> +#define SM_NOT_IDLE_MASK		BIT(0)
> +#define TX_PKT_DONE_MASK		BIT(1)
> +#define DPHY_DIRECTION_MASK		BIT(2)
> +#define TX_FIFO_OVFLW_MASK		BIT(3)
> +#define TX_FIFO_UDFLW_MASK		BIT(4)
> +#define RX_FIFO_OVFLW_MASK		BIT(5)
> +#define RX_FIFO_UDFLW_MASK		BIT(6)
> +#define RX_PKT_HDR_RCVD_MASK		BIT(7)
> +#define RX_PKT_PAYLOAD_DATA_RCVD_MASK	BIT(8)
> +#define BTA_TIMEOUT_MASK		BIT(29)
> +#define LP_RX_TIMEOUT_MASK		BIT(30)
> +#define HS_TX_TIMEOUT_MASK		BIT(31)
> +
> +#define IRQ_MASK2			0x2ac
> +#define SINGLE_BIT_ECC_ERR_MASK		BIT(0)
> +#define MULTI_BIT_ECC_ERR_MASK		BIT(1)
> +#define CRC_ERR_MASK			BIT(2)
> +
> +extern const struct mipi_dsi_host_ops nwl_dsi_host_ops;
> +
> +irqreturn_t nwl_dsi_irq_handler(int irq, void *data);
> +int nwl_dsi_enable(struct imx_nwl_dsi *dsi);
> +int nwl_dsi_disable(struct imx_nwl_dsi *dsi);
> +int nwl_dsi_get_dphy_params(struct imx_nwl_dsi *dsi,
> +			    const struct drm_display_mode *mode,
> +			    union phy_configure_opts *phy_opts);
> +
> +#endif /* __NWL_DSI_H__ */

Guido Günther July 31, 2019, 2:35 p.m. UTC | #5

Hi Fabio,
thanks for having a look! I followed most of your comments, there's some
things i'm unsure, see below:

On Fri, Jul 26, 2019 at 05:01:52PM -0300, Fabio Estevam wrote:
> Hi Guido,
> 
> Thanks for your work on this driver!
> 
> On Wed, Jul 24, 2019 at 12:52 PM Guido Günther <[e-mail]> wrote:
> 
> > --- /dev/null
> > +++ b/drivers/gpu/drm/bridge/imx-nwl/Kconfig
> > @@ -0,0 +1,15 @@
> > +config DRM_IMX_NWL_DSI
> > +       tristate "Support for Northwest Logic MIPI DSI Host controller"
> > +       depends on DRM && (ARCH_MXC || ARCH_MULTIPLATFORM || COMPILE_TEST)
> 
> 
> This IP could potentially be found on other SoCs, so no need to make
> it depend on ARCH_MXC.

Done.

> > +#include <drm/drm_atomic_helper.h>
> > +#include <drm/drm_of.h>
> > +#include <drm/drm_panel.h>
> > +#include <drm/drm_print.h>
> > +#include <drm/drm_probe_helper.h>
> > +#include <linux/clk-provider.h>
> > +#include <linux/clk.h>
> > +#include <linux/component.h>
> > +#include <linux/gpio/consumer.h>
> 
> I did not find gpio AP used in this driver.

Dropped the include.

> 
> > +static void imx_nwl_dsi_set_clocks(struct imx_nwl_dsi *dsi, bool enable)
> 
> Better make it to return 'int' instead...

Done, but see below.

> 
> > +{
> > +       struct device *dev = dsi->dev;
> > +       const char *id;
> > +       struct clk *clk;
> > +       unsigned long new_rate, cur_rate;
> > +       bool enabled;
> > +       size_t i;
> > +       int ret;
> > +
> > +       DRM_DEV_DEBUG_DRIVER(dev, "%sabling platform clocks",
> 
> Please remove the letter 's' from 'sabling'.

The idea is to have

    "%sabling platform clocks", enable ? "en" : "dis");

depending whether clocks are enabled/disabled.

> 
> > +                            enable ? "en" : "dis");
> > +                       ret = clk_prepare_enable(clk);
> > +                       if (ret < 0) {
> > +                               DRM_DEV_ERROR(dev, "Failed to enable clock %s",
> > +                                             id);
> 
> and propagate the error in case of clk_prepare_enable() failure.

done.

> 
> > +                       }
> > +                       dsi->clk_config[i].enabled = true;
> > +                       cur_rate = clk_get_rate(clk);
> > +                       DRM_DEV_DEBUG_DRIVER(
> > +                               dev, "Enabled %s clk (rate: req=%lu act=%lu)\n",
> > +                               id, new_rate, cur_rate);
> > +               } else if (enabled) {
> > +                       clk_disable_unprepare(clk);
> > +                       dsi->clk_config[i].enabled = false;
> > +                       DRM_DEV_DEBUG_DRIVER(dev, "Disabled %s clk\n", id);
> > +               }
> > +       }
> > +}
> > +
> > +static void imx_nwl_dsi_enable(struct imx_nwl_dsi *dsi)
> 
> Same here. Please return 'int' instead.

This is from drm_bridge_funcs so the prototype is fixed. I'm not sure
how what's the best way to bubble up fatal errors through the drm layer?

> > +{
> > +       struct device *dev = dsi->dev;
> > +       int ret;
> > +
> > +       imx_nwl_dsi_set_clocks(dsi, true);
> > +
> > +       ret = dsi->pdata->poweron(dsi);
> > +       if (ret < 0)
> > +               DRM_DEV_ERROR(dev, "Failed to power on DSI (%d)\n", ret);
> 
> If the power domain failed to turn on, it is better to propagate the
> error.

If fixed the return type here as well but this will again get lost in
`_pre_enable` which again is void in drm_bridge_funcs (see below).

> 
> > +       phy_ref_rate = clk_get_rate(dsi->phy_ref_clk);
> > +       DRM_DEV_DEBUG_DRIVER(dev, "PHY at ref rate: %lu\n", phy_ref_rate);
> > +       if (ret < 0) {
> 
> This check looks wrong. At this point ret is always 0.

Fixed.

> 
> > +               DRM_DEV_ERROR(dsi->dev,
> > +                             "Cannot setup PHY for mode: %ux%u @%d Hz\n",
> > +                             adjusted_mode->hdisplay, adjusted_mode->vdisplay,
> > +                             adjusted_mode->clock);
> > +               DRM_DEV_ERROR(dsi->dev, "PHY ref clk: %lu, bit clk: %lu\n",
> > +                             phy_ref_rate, new_cfg.mipi_dphy.hs_clk_rate);
> > +       } else {
> > +               /* Save the new desired phy config */
> > +               memcpy(&dsi->phy_cfg, &new_cfg, sizeof(new_cfg));
> > +       }
> > +
> > +       /* LCDIF + NWL needs active high sync */
> 
> Would this still work if DCSS is used instead?

I'll check once there's a DCSS driver that can drive this. The current
vendor one is bound to imx-displays-subsystem and cant' drive a bridge.

> 
> > +       adjusted_mode->flags |= (DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
> > +       adjusted_mode->flags &= ~(DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC);
> > +
> > +       drm_display_mode_to_videomode(adjusted_mode, &dsi->vm);
> > +       drm_mode_debug_printmodeline(adjusted_mode);
> > +
> > +       return ret == 0;
> 
> At this point ret is always 0.

Right, there was some more logic in there that got removed. Changed to
always signal success.

> 
> > +static void imx_nwl_dsi_bridge_pre_enable(struct drm_bridge *bridge)
> > +{
> > +       struct imx_nwl_dsi *dsi = bridge_to_dsi(bridge);
> > +
> > +       if (dsi->dpms_mode == DRM_MODE_DPMS_ON)
> > +               return;
> > +
> > +       imx_nwl_select_input_source(dsi);
> 
> This function is i.MX8M specific, so better protect it to run only for
> the i.MX8M variant.

Moved into imx_nwl_platform_data.

> 
> > +       pm_runtime_get_sync(dsi->dev);
> > +       imx_nwl_dsi_enable(dsi);
> > +       nwl_dsi_enable(dsi);
> 
> Please check the error and propagate in the case of failure.

This one is again hooked in from drm_bridge_funcs which is void.

> 
> > +       dsi->dpms_mode = DRM_MODE_DPMS_ON;
> > +}
> > +
> 
> > +       dsi->csr = syscon_regmap_lookup_by_phandle(np, "csr");
> > +       if (IS_ERR(dsi->csr) && dsi->pdata->ext_regs & IMX_REG_CSR) {
> > +               ret = PTR_ERR(dsi->csr);
> > +               DRM_DEV_ERROR(dsi->dev, "Failed to get CSR regmap: %d\n",
> 
> In this function (and globally in the driver) there is a mix of
> DRM_DEV_ERROR() and dev_err().
> 
> Can we just pick one of the two and use it consistently?
> 
> Not sure what is the norm in drm code, but IMHO dev_err() looks
> prettier :-)

I went for DRM_DEV_ERROR() since that what i used in the rest of the
driver and these ones were omission. Hope that's o.k.

> 
> > +
> > +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +       base = devm_ioremap_resource(dsi->dev, res);
> 
> Could use devm_platform_ioremap_resource(), which makes it simpler.

Done.

> 
> > +err_cleanup:
> > +       devm_free_irq(dev, dsi->irq, dsi);
> 
> No need to call devm_free_irq() here. The devm functions do not need
> to be freed on probe.

Removed.

> 
> > diff --git a/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.c b/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.c
> > new file mode 100644
> > index 000000000000..0e1463af162f
> > --- /dev/null
> > +++ b/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.c
> > @@ -0,0 +1,745 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * NWL DSI host driver
> > + *
> > + * Copyright (C) 2017 NXP
> > + * Copyright (C) 2019 Purism SPC
> > + */
> > +
> > +#include <asm/unaligned.h>
> 
> Is this asm header required?

I dropped it after removing get_unaligned_le32.

> 
> > +/*
> > + * DSI Video mode
> > + */
> 
> Single line comment would suffice.
> 
> > +#define VIDEO_MODE_BURST_MODE_WITH_SYNC_PULSES         0
> > +#define VIDEO_MODE_NON_BURST_MODE_WITH_SYNC_EVENTS     BIT(0)
> > +#define VIDEO_MODE_BURST_MODE                          BIT(1)
> > +
> > +/*
> > + * DPI color coding
> > + */
> 
> Ditto.
> 
> > +#define DPI_16_BIT_565_PACKED  0
> > +#define DPI_16_BIT_565_ALIGNED 1
> > +#define DPI_16_BIT_565_SHIFTED 2
> > +#define DPI_18_BIT_PACKED      3
> > +#define DPI_18_BIT_ALIGNED     4
> > +#define DPI_24_BIT             5
> > +
> > +/*
> > + * DPI Pixel format
> > + */
> 
> Ditto.

all fixed

> 
> > +#define PIXEL_FORMAT_16  0
> > +#define PIXEL_FORMAT_18  BIT(0)
> > +#define PIXEL_FORMAT_18L BIT(1)
> > +#define PIXEL_FORMAT_24  (BIT(0) | BIT(1))
> > +
> > +enum transfer_direction { DSI_PACKET_SEND, DSI_PACKET_RECEIVE };
> > +
> > +struct mipi_dsi_transfer {
> > +       const struct mipi_dsi_msg *msg;
> > +       struct mipi_dsi_packet packet;
> > +       struct completion completed;
> > +
> > +       int status; /* status of transmission */
> > +       enum transfer_direction direction;
> > +       bool need_bta;
> > +       u8 cmd;
> > +       u16 rx_word_count;
> > +       size_t tx_len; /* bytes sent */
> > +       size_t rx_len; /* bytes received */
> > +};
> 
> The comments here are kind of obvious, so I would just remove them.

I wanted to have the unit here so i changed to /* in bytes */

> 
> > +static inline int nwl_dsi_write(struct imx_nwl_dsi *dsi, unsigned int reg,
> 
> inline can be dropped.

done.
> 
> > +                               u32 val)
> > +{
> > +       int ret;
> > +
> > +       ret = regmap_write(dsi->regmap, reg, val);
> > +       if (ret < 0)
> > +               DRM_DEV_ERROR(dsi->dev,
> > +                             "Failed to write NWL DSI reg 0x%x: %d\n", reg,
> > +                             ret);
> > +       return ret;
> > +}
> > +
> > +static inline u32 nwl_dsi_read(struct imx_nwl_dsi *dsi, u32 reg)
> 
> Same here.

done.

> > +{
> > +       unsigned int val;
> > +       int ret;
> > +
> > +       ret = regmap_read(dsi->regmap, reg, &val);
> > +       if (ret < 0)
> > +               DRM_DEV_ERROR(dsi->dev, "Failed to read NWL DSI reg 0x%x: %d\n",
> > +                             reg, ret);
> > +
> > +       return val;
> > +}
> 
> It seems that we could simply use regmap_read/write() directly instead
> of these functions.

I've checked some other drm drivers most of them seem to
regmap_{read,write} without looking at errors. While we can't do
anything sensible when writing fails it's seems at least useful to print
an error. I've seen these happening and the messages were very useful
for debugging so if possible i'd keep them.

> > +int nwl_dsi_get_dphy_params(struct imx_nwl_dsi *dsi,
> > +                           const struct drm_display_mode *mode,
> > +                           union phy_configure_opts *phy_opts)
> > +{
> > +       unsigned long rate;
> > +
> > +       if (dsi->lanes < 1 || dsi->lanes > 4)
> > +               return -EINVAL;
> > +
> > +       /*
> > +        * So far the DPHY spec minimal timings work for both mixel
> > +        * dphy and nwl dsi host
> > +        */
> > +       phy_mipi_dphy_get_default_config(
> > +               mode->crtc_clock * 1000,
> > +               mipi_dsi_pixel_format_to_bpp(dsi->format), dsi->lanes,
> > +               &phy_opts->mipi_dphy);
> > +       rate = clk_get_rate(dsi->tx_esc_clk);
> > +       DRM_DEV_DEBUG_DRIVER(dsi->dev, "LP clk is @%lu Hz\n", rate);
> > +       phy_opts->mipi_dphy.lp_clk_rate = rate;
> > +
> > +       return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(nwl_dsi_get_dphy_params);
> 
> Does it really need to be exported? Why can't it be placed inside
> nwl-drv.c and be made static?

Moved.

> 
> > +/**
> 
> /* is enough

Fixed.

> 
> 
> > + * ui2bc - UI time periods to byte clock cycles
> > + */
> > +static u32 ui2bc(struct imx_nwl_dsi *dsi, unsigned long long ui)
> > +{
> > +       int bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
> > +
> > +       return DIV_ROUND_UP(ui * dsi->lanes, dsi->vm.pixelclock * bpp);
> > +}
> > +
> > +#define USEC_PER_SEC 1000000L
> 
> This definition already exists in include/linux/time64.h. No need to
> redefine it.

Dropped that define.

> 
> > +static int nwl_dsi_enable_tx_clock(struct imx_nwl_dsi *dsi)
> > +{
> > +       struct device *dev = dsi->dev;
> > +       int ret;
> > +
> > +       ret = clk_prepare_enable(dsi->tx_esc_clk);
> > +       if (ret < 0) {
> > +               DRM_DEV_ERROR(dev, "Failed to enable tx_esc clk: %d\n", ret);
> > +               return ret;
> > +       }
> > +
> > +       DRM_DEV_DEBUG_DRIVER(dev, "Enabled tx_esc clk @%lu Hz\n",
> > +                            clk_get_rate(dsi->tx_esc_clk));
> > +       return 0;
> > +}
> 
> Do we really need this function? It looks like it would be simpler
> just to call clk_prepare_enable() directly.

Dropped since it's only used once, there were more users before.

> 
> > +
> > +static int nwl_dsi_enable_rx_clock(struct imx_nwl_dsi *dsi)
> > +{
> > +       struct device *dev = dsi->dev;
> > +       int ret;
> > +
> > +       ret = clk_prepare_enable(dsi->rx_esc_clk);
> > +       if (ret < 0) {
> > +               DRM_DEV_ERROR(dev, "Failed to enable rx_esc clk: %d\n", ret);
> > +               return ret;
> > +       }
> > +
> > +       DRM_DEV_DEBUG_DRIVER(dev, "Enabled rx_esc clk @%lu Hz\n",
> > +                            clk_get_rate(dsi->rx_esc_clk));
> > +       return 0;
> > +}
> 
> Same here.

Dropped since it's only used once.

> > +static ssize_t nwl_dsi_host_transfer(struct mipi_dsi_host *dsi_host,
> > +                                    const struct mipi_dsi_msg *msg)
> > +{
> > +       struct imx_nwl_dsi *dsi =
> > +               container_of(dsi_host, struct imx_nwl_dsi, dsi_host);
> > +       struct mipi_dsi_transfer xfer;
> > +       ssize_t ret = 0;
> > +
> > +       /* Create packet to be sent */
> > +       dsi->xfer = &xfer;
> > +       ret = mipi_dsi_create_packet(&xfer.packet, msg);
> > +       if (ret < 0) {
> > +               dsi->xfer = NULL;
> > +               return ret;
> > +       }
> > +
> > +       if ((msg->type & MIPI_DSI_GENERIC_READ_REQUEST_0_PARAM ||
> > +            msg->type & MIPI_DSI_GENERIC_READ_REQUEST_1_PARAM ||
> > +            msg->type & MIPI_DSI_GENERIC_READ_REQUEST_2_PARAM ||
> > +            msg->type & MIPI_DSI_DCS_READ) &&
> > +           msg->rx_len > 0 && msg->rx_buf != NULL)
> > +               xfer.direction = DSI_PACKET_RECEIVE;
> > +       else
> > +               xfer.direction = DSI_PACKET_SEND;
> > +
> > +       xfer.need_bta = (xfer.direction == DSI_PACKET_RECEIVE);
> > +       xfer.need_bta |= (msg->flags & MIPI_DSI_MSG_REQ_ACK) ? 1 : 0;
> > +       xfer.msg = msg;
> > +       xfer.status = -ETIMEDOUT;
> > +       xfer.rx_word_count = 0;
> > +       xfer.rx_len = 0;
> > +       xfer.cmd = 0x00;
> > +       if (msg->tx_len > 0)
> > +               xfer.cmd = ((u8 *)(msg->tx_buf))[0];
> > +       init_completion(&xfer.completed);
> > +
> > +       nwl_dsi_enable_rx_clock(dsi);
> 
> This may fail, so better check the error.
> 
> ret = clk_prepare_enable()
> if (ret < 0)
>    return ret;

Done.

> > +irqreturn_t nwl_dsi_irq_handler(int irq, void *data)
> > +{
> > +       u32 irq_status;
> > +       struct imx_nwl_dsi *dsi = data;
> > +
> > +       irq_status = nwl_dsi_read(dsi, IRQ_STATUS);
> > +
> > +       if (irq_status & TX_PKT_DONE || irq_status & RX_PKT_HDR_RCVD ||
> > +           irq_status & RX_PKT_PAYLOAD_DATA_RCVD)
> > +               nwl_dsi_finish_transmission(dsi, irq_status);
> > +
> > +       return IRQ_HANDLED;
> > +}
> > +EXPORT_SYMBOL_GPL(nwl_dsi_irq_handler);
> 
> What about placing this function inside nwl-drv.c and make it static?

Then nwl_dsi_finish_transmission would need to either be moved as well
or we'd have another non-static function. I'd like to keeping the irq
handling in one file and only have the registration over in imx-nwl-drv.
I've dropped the EXPORT_SYMBOL_GPL though.

> > +
> > +int nwl_dsi_enable(struct imx_nwl_dsi *dsi)
> > +{
> > +       struct device *dev = dsi->dev;
> > +       union phy_configure_opts *phy_cfg = &dsi->phy_cfg;
> > +       int ret;
> > +
> > +       if (!dsi->lanes) {
> > +               DRM_DEV_ERROR(dev, "Need DSI lanes: %d\n", dsi->lanes);
> > +               return -EINVAL;
> > +       }
> > +
> > +       ret = phy_init(dsi->phy);
> > +       if (ret < 0) {
> > +               DRM_DEV_ERROR(dev, "Failed to init DSI phy: %d\n", ret);
> > +               return ret;
> > +       }
> > +
> > +       ret = phy_configure(dsi->phy, phy_cfg);
> > +       if (ret < 0) {
> > +               DRM_DEV_ERROR(dev, "Failed to configure DSI phy: %d\n", ret);
> > +               return ret;
> > +       }
> > +
> > +       ret = nwl_dsi_enable_tx_clock(dsi);
> > +       if (ret < 0) {
> > +               DRM_DEV_ERROR(dev, "Failed to enable tx clock: %d\n", ret);
> > +               return ret;
> > +       }
> > +
> > +       ret = nwl_dsi_config_host(dsi);
> > +       if (ret < 0) {
> > +               DRM_DEV_ERROR(dev, "Failed to set up DSI: %d", ret);
> > +               return ret;
> > +       }
> > +
> > +       ret = nwl_dsi_config_dpi(dsi);
> > +       if (ret < 0) {
> > +               DRM_DEV_ERROR(dev, "Failed to set up DPI: %d", ret);
> > +               return ret;
> > +       }
> > +
> > +       ret = phy_power_on(dsi->phy);
> > +       if (ret < 0) {
> > +               DRM_DEV_ERROR(dev, "Failed to power on DPHY (%d)\n", ret);
> > +               return ret;
> > +       }
> > +
> > +       nwl_dsi_init_interrupts(dsi);
> > +
> > +       return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(nwl_dsi_enable);
> 
> Same here.

The idea was to keep the dsi related operations here. Dropped
EXPORT_SYMBOL_GPL though.

> 
> > +
> > +int nwl_dsi_disable(struct imx_nwl_dsi *dsi)
> > +{
> > +       struct device *dev = dsi->dev;
> > +
> > +       DRM_DEV_DEBUG_DRIVER(dev, "Disabling clocks and phy\n");
> > +
> > +       phy_power_off(dsi->phy);
> > +       phy_exit(dsi->phy);
> > +
> > +       /* Disabling the clock before the phy breaks enabling dsi again */
> > +       clk_disable_unprepare(dsi->tx_esc_clk);
> > +
> > +       return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(nwl_dsi_disable);
> 
> Same here.

Same as above. I can move things if wanted but then it might make sense
to only use one large file which I avoided so we can have a split
between DSI operations and probing / bridge chaining and platform
specific functions.

Thanks again for having a look,
 -- Guido

Guido Günther July 31, 2019, 2:38 p.m. UTC | #6

Hi,
On Sat, Jul 27, 2019 at 05:04:44AM +0300, Laurent Pinchart wrote:
> Hello,
> 
> On Fri, Jul 26, 2019 at 05:01:52PM -0300, Fabio Estevam wrote:
> > Hi Guido,
> > 
> > Thanks for your work on this driver!
> > 
> > On Wed, Jul 24, 2019 at 12:52 PM Guido Günther <[e-mail]> wrote:
> > 
> > > --- /dev/null
> > > +++ b/drivers/gpu/drm/bridge/imx-nwl/Kconfig
> > > @@ -0,0 +1,15 @@
> > > +config DRM_IMX_NWL_DSI
> > > +       tristate "Support for Northwest Logic MIPI DSI Host controller"
> > > +       depends on DRM && (ARCH_MXC || ARCH_MULTIPLATFORM || COMPILE_TEST)
> > 
> > This IP could potentially be found on other SoCs, so no need to make
> > it depend on ARCH_MXC.
> 
> I'd go even further and not use the prefix imx in the driver name or
> anywhere in the code.

My idea was to do that when another possible user comes up to see what
can be shared but I can do that for v2.
Cheers,
 -- Guido

> 
> [snip]
> 
> -- 
> Regards,
> 
> Laurent Pinchart
>

Fabio Estevam July 31, 2019, 2:43 p.m. UTC | #7

Hi Guido,

On Wed, Jul 31, 2019 at 11:35 AM Guido Günther <[e-mail]> wrote:

> The idea is to have
>
>     "%sabling platform clocks", enable ? "en" : "dis");
>
> depending whether clocks are enabled/disabled.

Yes, I understood the idea, but this would print:

ensabling or dissabling :-)

> > Same here. Please return 'int' instead.
>
> This is from drm_bridge_funcs so the prototype is fixed. I'm not sure
> how what's the best way to bubble up fatal errors through the drm layer?

Ok, so let's not change this one.

> I went for DRM_DEV_ERROR() since that what i used in the rest of the
> driver and these ones were omission. Hope that's o.k.

No strong preferences here. I just think dev_err() easier to type and shorter.

Thanks for this work!

Jernej Škrabec July 31, 2019, 4:40 p.m. UTC | #8

Hi!

Dne sreda, 31. julij 2019 ob 16:43:47 CEST je Fabio Estevam napisal(a):
> Hi Guido,
> 
> On Wed, Jul 31, 2019 at 11:35 AM Guido Günther <[e-mail]> wrote:
> > The idea is to have
> > 
> >     "%sabling platform clocks", enable ? "en" : "dis");
> > 
> > depending whether clocks are enabled/disabled.
> 
> Yes, I understood the idea, but this would print:
> 
> ensabling or dissabling :-)

No, it wouldn't. That extra "s" is part of "%s", e.g. part of format specifier.

Best regards,
Jernej

> 
> > > Same here. Please return 'int' instead.
> > 
> > This is from drm_bridge_funcs so the prototype is fixed. I'm not sure
> > how what's the best way to bubble up fatal errors through the drm layer?
> 
> Ok, so let's not change this one.
> 
> > I went for DRM_DEV_ERROR() since that what i used in the rest of the
> > driver and these ones were omission. Hope that's o.k.
> 
> No strong preferences here. I just think dev_err() easier to type and
> shorter.
> 
> Thanks for this work!

Guido Günther July 31, 2019, 4:54 p.m. UTC | #9

Hi,
On Wed, Jul 31, 2019 at 11:43:47AM -0300, Fabio Estevam wrote:
> Hi Guido,
> 
> On Wed, Jul 31, 2019 at 11:35 AM Guido Günther <[e-mail]> wrote:
> 
> > The idea is to have
> >
> >     "%sabling platform clocks", enable ? "en" : "dis");
> >
> > depending whether clocks are enabled/disabled.
> 
> Yes, I understood the idea, but this would print:
> 
> ensabling or dissabling :-)

The 's' is from the '%s' format specifier:

[ 2610.804174] imx-nwl-dsi 30a00000.mipi_dsi: [drm:imx_nwl_dsi_bridge_disable] disabling platform clocks
[ 2710.996279] imx-nwl-dsi 30a00000.mipi_dsi: [drm:imx_nwl_dsi_bridge_pre_enable] enabling platform clocks

I'll change that to use the full strings though since i also had to look
twice to be sure there's no double 's'.

> 
> > > Same here. Please return 'int' instead.
> >
> > This is from drm_bridge_funcs so the prototype is fixed. I'm not sure
> > how what's the best way to bubble up fatal errors through the drm layer?
> 
> Ok, so let's not change this one.
> 
> > I went for DRM_DEV_ERROR() since that what i used in the rest of the
> > driver and these ones were omission. Hope that's o.k.
> 
> No strong preferences here. I just think dev_err() easier to type and shorter.
> 
> Thanks for this work!

Thanks again for having a look!
 -- Guido

Fabio Estevam July 31, 2019, 5:40 p.m. UTC | #10

On Wed, Jul 31, 2019 at 1:40 PM Jernej Škrabec <[e-mail]> wrote:

> > Yes, I understood the idea, but this would print:
> >
> > ensabling or dissabling :-)
>
> No, it wouldn't. That extra "s" is part of "%s", e.g. part of format specifier.

Ops, you are right. Sorry about that!

Guido Günther Aug. 9, 2019, 4:25 p.m. UTC | #11

Hi Laurent,

thanks for the review! Most of it seemed clear how to fix for the rest
i've put some questions below:

On Sat, Jul 27, 2019 at 05:47:00AM +0300, Laurent Pinchart wrote:
> Hello Guido,
> 
> Thank you for the patch.
> 
> On Wed, Jul 24, 2019 at 05:52:26PM +0200, Guido Günther wrote:
> > This adds initial support for the NWL MIPI DSI Host controller found on
> > i.MX8 SoCs.
> > 
> > It adds support for the i.MX8MQ but the same IP can be found on
> > e.g. the i.MX8QXP.
> > 
> > It has been tested on the Librem 5 devkit using mxsfb.
> > 
> > Signed-off-by: Guido Günther <[e-mail]>
> > Co-developed-by: Robert Chiras <[e-mail]>
> > ---
> >  drivers/gpu/drm/bridge/Kconfig           |   2 +
> >  drivers/gpu/drm/bridge/Makefile          |   1 +
> >  drivers/gpu/drm/bridge/imx-nwl/Kconfig   |  15 +
> >  drivers/gpu/drm/bridge/imx-nwl/Makefile  |   2 +
> >  drivers/gpu/drm/bridge/imx-nwl/nwl-drv.c | 529 ++++++++++++++++
> >  drivers/gpu/drm/bridge/imx-nwl/nwl-drv.h |  72 +++
> >  drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.c | 745 +++++++++++++++++++++++
> >  drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.h | 111 ++++
> >  8 files changed, 1477 insertions(+)
> >  create mode 100644 drivers/gpu/drm/bridge/imx-nwl/Kconfig
> >  create mode 100644 drivers/gpu/drm/bridge/imx-nwl/Makefile
> >  create mode 100644 drivers/gpu/drm/bridge/imx-nwl/nwl-drv.c
> >  create mode 100644 drivers/gpu/drm/bridge/imx-nwl/nwl-drv.h
> >  create mode 100644 drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.c
> >  create mode 100644 drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.h
> > 
> > diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> > index a6eec908c43e..38c3145a7e57 100644
> > --- a/drivers/gpu/drm/bridge/Kconfig
> > +++ b/drivers/gpu/drm/bridge/Kconfig
> > @@ -152,6 +152,8 @@ source "drivers/gpu/drm/bridge/analogix/Kconfig"
> >  
> >  source "drivers/gpu/drm/bridge/adv7511/Kconfig"
> >  
> > +source "drivers/gpu/drm/bridge/imx-nwl/Kconfig"
> > +
> 
> As this doesn't seem to be an i.MX-specific IP, I wouldn't use the name
> imx in file names or in the code, at least in the parts that are not
> NXP-specific.

O.k. Since i've not seen other SoCs using this ip core I wasn't sure
what would be sharable but we'll figure that out. Renamed to nwl-dsi/

> >  source "drivers/gpu/drm/bridge/synopsys/Kconfig"
> >  
> >  endmenu
> > diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> > index 4934fcf5a6f8..904a9eb3a20a 100644
> > --- a/drivers/gpu/drm/bridge/Makefile
> > +++ b/drivers/gpu/drm/bridge/Makefile
> > @@ -16,4 +16,5 @@ obj-$(CONFIG_DRM_ANALOGIX_DP) += analogix/
> >  obj-$(CONFIG_DRM_I2C_ADV7511) += adv7511/
> >  obj-$(CONFIG_DRM_TI_SN65DSI86) += ti-sn65dsi86.o
> >  obj-$(CONFIG_DRM_TI_TFP410) += ti-tfp410.o
> > +obj-y += imx-nwl/
> >  obj-y += synopsys/
> > diff --git a/drivers/gpu/drm/bridge/imx-nwl/Kconfig b/drivers/gpu/drm/bridge/imx-nwl/Kconfig
> > new file mode 100644
> > index 000000000000..822dba1b380a
> > --- /dev/null
> > +++ b/drivers/gpu/drm/bridge/imx-nwl/Kconfig
> > @@ -0,0 +1,15 @@
> > +config DRM_IMX_NWL_DSI
> > +	tristate "Support for Northwest Logic MIPI DSI Host controller"
> > +	depends on DRM && (ARCH_MXC || ARCH_MULTIPLATFORM || COMPILE_TEST)
> > +	depends on COMMON_CLK
> > +	depends on OF && HAS_IOMEM
> > +	select DRM_KMS_HELPER
> > +	select DRM_MIPI_DSI
> > +	select DRM_PANEL_BRIDGE
> > +	select GENERIC_PHY_MIPI_DPHY
> > +	select MFD_SYSCON
> > +	select REGMAP_MMIO
> > +	help
> > +	  This enables the Northwest Logic MIPI DSI Host controller as
> > +	  found on NXP's i.MX8 Processors.
> > +
> > diff --git a/drivers/gpu/drm/bridge/imx-nwl/Makefile b/drivers/gpu/drm/bridge/imx-nwl/Makefile
> > new file mode 100644
> > index 000000000000..9fa63483da5b
> > --- /dev/null
> > +++ b/drivers/gpu/drm/bridge/imx-nwl/Makefile
> > @@ -0,0 +1,2 @@
> > +imx-nwl-objs := nwl-drv.o nwl-dsi.o
> > +obj-$(CONFIG_DRM_IMX_NWL_DSI) += imx-nwl.o
> > diff --git a/drivers/gpu/drm/bridge/imx-nwl/nwl-drv.c b/drivers/gpu/drm/bridge/imx-nwl/nwl-drv.c
> > new file mode 100644
> > index 000000000000..451f8f067c6f
> > --- /dev/null
> > +++ b/drivers/gpu/drm/bridge/imx-nwl/nwl-drv.c
> > @@ -0,0 +1,529 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * i.MX8 NWL MIPI DSI host driver
> > + *
> > + * Copyright (C) 2017 NXP
> > + * Copyright (C) 2019 Purism SPC
> > + */
> > +
> > +#include <drm/drm_atomic_helper.h>
> > +#include <drm/drm_of.h>
> > +#include <drm/drm_panel.h>
> > +#include <drm/drm_print.h>
> > +#include <drm/drm_probe_helper.h>
> > +#include <linux/clk-provider.h>
> 
> This doesn't seem to be needed.

Dropped.

> 
> > +#include <linux/clk.h>
> > +#include <linux/component.h>
> 
> Same here.

Dropped (it was a component driver before).

> > +#include <linux/gpio/consumer.h>
> > +#include <linux/irq.h>
> > +#include <linux/mfd/syscon.h>
> > +#include <linux/mfd/syscon/imx8mq-iomuxc-gpr.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/of_platform.h>
> > +#include <linux/phy/phy.h>
> > +#include <linux/regmap.h>
> > +#include <linux/sys_soc.h>
> > +#include <video/videomode.h>
> > +
> > +#include "nwl-drv.h"
> > +#include "nwl-dsi.h"
> > +
> > +#define DRV_NAME "imx-nwl-dsi"
> > +
> > +/* 8MQ SRC specific registers */
> > +#define SRC_MIPIPHY_RCR	0x28
> > +#define RESET_BYTE_N	BIT(1)
> > +#define RESET_N		BIT(2)
> > +#define DPI_RESET_N	BIT(3)
> > +#define ESC_RESET_N	BIT(4)
> > +#define PCLK_RESET_N	BIT(5)
> > +
> > +/* Possible clocks */
> > +#define CLK_PIXEL	"pixel"
> > +#define CLK_CORE	"core"
> > +#define CLK_BYPASS	"bypass"
> > +
> > +enum imx_ext_regs {
> > +	IMX_REG_CSR = BIT(1),
> > +	IMX_REG_SRC = BIT(2),
> > +	IMX_REG_GPR = BIT(3),
> > +};
> > +
> > +static const struct regmap_config nwl_dsi_regmap_config = {
> > +	.reg_bits = 16,
> > +	.val_bits = 32,
> > +	.reg_stride = 4,
> > +	.max_register = IRQ_MASK2,
> > +	.name = DRV_NAME,
> > +};
> > +
> > +struct imx_nwl_platform_data {
> > +	int (*poweron)(struct imx_nwl_dsi *dsi);
> > +	int (*poweroff)(struct imx_nwl_dsi *dsi);
> > +	u32 ext_regs; /* required external registers */
> > +	struct imx_nwl_clk_config clk_config[NWL_MAX_PLATFORM_CLOCKS];
> > +};
> > +
> > +static inline struct imx_nwl_dsi *bridge_to_dsi(struct drm_bridge *bridge)
> > +{
> > +	return container_of(bridge, struct imx_nwl_dsi, bridge);
> > +}
> > +
> > +static void imx_nwl_dsi_set_clocks(struct imx_nwl_dsi *dsi, bool enable)
> > +{
> > +	struct device *dev = dsi->dev;
> > +	const char *id;
> > +	struct clk *clk;
> > +	unsigned long new_rate, cur_rate;
> > +	bool enabled;
> > +	size_t i;
> > +	int ret;
> > +
> > +	DRM_DEV_DEBUG_DRIVER(dev, "%sabling platform clocks",
> > +			     enable ? "en" : "dis");
> > +	for (i = 0; i < ARRAY_SIZE(dsi->pdata->clk_config); i++) {
> > +		if (!dsi->clk_config[i].present)
> > +			continue;
> > +		id = dsi->clk_config[i].id;
> > +		clk = dsi->clk_config[i].clk;
> > +		new_rate = dsi->clk_config[i].rate;
> > +		cur_rate = clk_get_rate(clk);
> > +		enabled = dsi->clk_config[i].enabled;
> > +
> > +		/* BYPASS clk must have the same rate as PHY_REF clk */
> > +		if (!strcmp(id, CLK_BYPASS))
> > +			new_rate = clk_get_rate(dsi->phy_ref_clk);
> > +
> > +		if (enable) {
> > +			if (enabled && new_rate != cur_rate)
> > +				clk_disable_unprepare(clk);
> > +			else if (enabled && new_rate == cur_rate)
> > +				continue;
> > +			if (new_rate > 0)
> > +				clk_set_rate(clk, new_rate);
> > +			ret = clk_prepare_enable(clk);
> > +			if (ret < 0) {
> > +				DRM_DEV_ERROR(dev, "Failed to enable clock %s",
> > +					      id);
> > +			}
> > +			dsi->clk_config[i].enabled = true;
> > +			cur_rate = clk_get_rate(clk);
> > +			DRM_DEV_DEBUG_DRIVER(
> > +				dev, "Enabled %s clk (rate: req=%lu act=%lu)\n",
> > +				id, new_rate, cur_rate);
> > +		} else if (enabled) {
> > +			clk_disable_unprepare(clk);
> > +			dsi->clk_config[i].enabled = false;
> > +			DRM_DEV_DEBUG_DRIVER(dev, "Disabled %s clk\n", id);
> > +		}
> > +	}
> > +}
> > +
> > +static void imx_nwl_dsi_enable(struct imx_nwl_dsi *dsi)
> > +{
> > +	struct device *dev = dsi->dev;
> > +	int ret;
> > +
> > +	imx_nwl_dsi_set_clocks(dsi, true);
> > +
> > +	ret = dsi->pdata->poweron(dsi);
> > +	if (ret < 0)
> > +		DRM_DEV_ERROR(dev, "Failed to power on DSI (%d)\n", ret);
> > +}
> > +
> > +static void imx_nwl_dsi_disable(struct imx_nwl_dsi *dsi)
> > +{
> > +	struct device *dev = dsi->dev;
> > +
> > +	if (dsi->dpms_mode != DRM_MODE_DPMS_ON)
> > +		return;
> > +
> 
> The DRM core should guarantee that the bridge won't be disabled twice,
> so I don't think you need this check. Similarly I think the enabled flag
> in the imx_nwl_clk_config structure can be removed.
  
Dropped and i also simplified the imx_nwl_clk_config - rates are supplied
via DT here anyway. 

> 
> > +	DRM_DEV_DEBUG_DRIVER(dev, "Disabling encoder");
> 
> Is this really needed ?

Dropped.

> > +	dsi->pdata->poweroff(dsi);
> > +	imx_nwl_dsi_set_clocks(dsi, false);
> > +}
> > +
> > +static void imx_nwl_select_input_source(struct imx_nwl_dsi *dsi)
> > +{
> > +	struct device_node *remote;
> > +	u32 mux_val = IMX8MQ_GPR13_MIPI_MUX_SEL;
> > +
> > +	remote = of_graph_get_remote_node(dsi->dev->of_node, 0, 0);
> > +	if (strcmp(remote->name, "lcdif") == 0)
> > +		mux_val = 0;
> > +

Getting it from dt spares us carrying around more platform specific
state. Should i change it anyway?

> 
> Can't you check the remote node at probe time instead of every time the
> bridge gets enabled, and program the IO mux accordingly there ?
> 
> This code is i.MX-specific, so it should be isolated in an operation in
> struct imx_nwl_platform_data.

Done.

> 
> > +	DRM_DEV_INFO(dsi->dev, "Using %s as input source\n",
> > +		     (mux_val) ? "DCSS" : "LCDIF");
> > +	regmap_update_bits(dsi->mux_sel, IOMUXC_GPR13,
> > +			   IMX8MQ_GPR13_MIPI_MUX_SEL, mux_val);
> > +	of_node_put(remote);
> > +}
> > +
> > +static void imx_nwl_dsi_bridge_disable(struct drm_bridge *bridge)
> > +{
> > +	struct imx_nwl_dsi *dsi = bridge_to_dsi(bridge);
> > +
> > +	if (dsi->dpms_mode != DRM_MODE_DPMS_ON)
> > +		return;
> > +
> > +	nwl_dsi_disable(dsi);
> > +	imx_nwl_dsi_disable(dsi);
> > +	pm_runtime_put_sync(dsi->dev);
> 
> Do you need a put_sync, wouldn't a put do ?

Switched to put() only.

> 
> > +	dsi->dpms_mode = DRM_MODE_DPMS_OFF;
> > +}
> > +
> > +static bool
> > +imx_nwl_dsi_bridge_mode_fixup(struct drm_bridge *bridge,
> > +			      const struct drm_display_mode *mode,
> > +			      struct drm_display_mode *adjusted_mode)
> > +{
> > +	struct imx_nwl_dsi *dsi = bridge_to_dsi(bridge);
> > +	struct device *dev = dsi->dev;
> > +	union phy_configure_opts new_cfg;
> > +	unsigned long phy_ref_rate;
> > +	int ret;
> > +
> > +	ret = nwl_dsi_get_dphy_params(dsi, adjusted_mode, &new_cfg);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	/*
> > +	 * If hs clock is unchanged, we're all good - all parameters are
> > +	 * derived from it atm.
> > +	 */
> > +	if (new_cfg.mipi_dphy.hs_clk_rate == dsi->phy_cfg.mipi_dphy.hs_clk_rate)
> > +		return true;
> > +
> > +	phy_ref_rate = clk_get_rate(dsi->phy_ref_clk);
> > +	DRM_DEV_DEBUG_DRIVER(dev, "PHY at ref rate: %lu\n", phy_ref_rate);
> > +	if (ret < 0) {
> 
> This can't happen. Or are you missing a function call before the check
> ?

The code used that a long time ago, fixed that path.

> 
> > +		DRM_DEV_ERROR(dsi->dev,
> > +			      "Cannot setup PHY for mode: %ux%u @%d Hz\n",
> > +			      adjusted_mode->hdisplay, adjusted_mode->vdisplay,
> > +			      adjusted_mode->clock);
> > +		DRM_DEV_ERROR(dsi->dev, "PHY ref clk: %lu, bit clk: %lu\n",
> > +			      phy_ref_rate, new_cfg.mipi_dphy.hs_clk_rate);
> > +	} else {
> > +		/* Save the new desired phy config */
> > +		memcpy(&dsi->phy_cfg, &new_cfg, sizeof(new_cfg));
> 
> The mode_fixup operation shall not change the device state, it can be
> called multiple times when trying modes.

Moved the parts to 'mode_set' instead.

> 
> > +	}
> > +
> > +	/* LCDIF + NWL needs active high sync */
> > +	adjusted_mode->flags |= (DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
> > +	adjusted_mode->flags &= ~(DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC);
> > +
> > +	drm_display_mode_to_videomode(adjusted_mode, &dsi->vm);
> > +	drm_mode_debug_printmodeline(adjusted_mode);
> > +
> > +	return ret == 0;
> 
> 	return 0;

mode_fixup wants a bool but that code is gone anyways.

> 
> > +}
> > +
> > +static enum drm_mode_status
> > +imx_nwl_dsi_bridge_mode_valid(struct drm_bridge *bridge,
> > +			      const struct drm_display_mode *mode)
> > +{
> > +	struct imx_nwl_dsi *dsi = bridge_to_dsi(bridge);
> > +	int bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
> > +
> > +	if (bpp < 0) {
> > +		DRM_DEV_ERROR(dsi->dev, "Invalid pixel format: %d\n",
> > +			      dsi->format);
> > +		return MODE_BAD;
> > +	}
> 
> The format isn't part of the mode, so this doesn't belong here. You
> should here instead check that the mode clock and other timing data
> (especially the visible resolution) are within the range supported by
> the device.

O.k. I've added a clock check derived from the spec instead.

> > +
> > +	return MODE_OK;
> > +}
> > +
> > +static void imx_nwl_dsi_bridge_pre_enable(struct drm_bridge *bridge)
> > +{
> > +	struct imx_nwl_dsi *dsi = bridge_to_dsi(bridge);
> > +
> > +	if (dsi->dpms_mode == DRM_MODE_DPMS_ON)
> > +		return;
> > +
> > +	imx_nwl_select_input_source(dsi);
> > +	pm_runtime_get_sync(dsi->dev);
> > +	imx_nwl_dsi_enable(dsi);
> > +	nwl_dsi_enable(dsi);
> > +	dsi->dpms_mode = DRM_MODE_DPMS_ON;
> > +}
> > +
> > +static int imx_nwl_dsi_bridge_attach(struct drm_bridge *bridge)
> > +{
> > +	struct imx_nwl_dsi *dsi = bridge->driver_private;
> > +	struct drm_encoder *encoder = bridge->encoder;
> > +
> > +	if (!encoder) {
> > +		DRM_DEV_ERROR(dsi->dev, "Parent encoder object not found\n");
> > +		return -ENODEV;
> > +	}
> 
> Can't this happen ?

Dropped.

> 
> > +
> > +	/* Set the encoder type as caller does not know it */
> > +	bridge->encoder->encoder_type = DRM_MODE_ENCODER_DSI;
> 
> The encoder type is quite meaningless and userspace should not depend on
> it, so I wouldn't set it here, especially that the encoder may not
> expect the bridge to override its type.

Dropped.

> 
> > +
> > +	/* Attach the panel-bridge to the dsi bridge */
> > +	return drm_bridge_attach(bridge->encoder, dsi->panel_bridge, bridge);
> > +}
> > +
> > +static void imx_nwl_dsi_bridge_detach(struct drm_bridge *bridge)
> > +{
> > +	struct imx_nwl_dsi *dsi = bridge->driver_private;
> > +
> > +	drm_of_panel_bridge_remove(dsi->dev->of_node, 1, 0);
> 
> This is already done in nwl_dsi_host_detach().

Dropped the whole detach.

> 
> > +}
> > +
> > +/* see dw-mipi-dsi.c */
> 
> What for ? :-)

Dropped.

> 
> > +static const struct drm_bridge_funcs imx_nwl_dsi_bridge_funcs = {
> > +	.pre_enable	= imx_nwl_dsi_bridge_pre_enable,
> > +	.disable    = imx_nwl_dsi_bridge_disable,
> > +	.mode_fixup = imx_nwl_dsi_bridge_mode_fixup,
> > +	.mode_valid = imx_nwl_dsi_bridge_mode_valid,
> > +	.attach	    = imx_nwl_dsi_bridge_attach,
> > +	.detach	    = imx_nwl_dsi_bridge_detach,
> > +};
> > +
> > +static int imx_nwl_dsi_parse_dt(struct imx_nwl_dsi *dsi)
> > +{
> > +	struct device_node *np = dsi->dev->of_node;
> > +	struct platform_device *pdev = to_platform_device(dsi->dev);
> > +	struct resource *res;
> > +	struct clk *clk;
> > +	const char *clk_id;
> > +	void __iomem *base;
> > +	int i, ret;
> > +
> > +	dsi->phy = devm_phy_get(dsi->dev, "dphy");
> > +	if (IS_ERR(dsi->phy)) {
> > +		ret = PTR_ERR(dsi->phy);
> > +		dev_err(dsi->dev, "Could not get PHY (%d)\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	/* Platform dependent clocks */
> > +	memcpy(dsi->clk_config, dsi->pdata->clk_config,
> > +	       sizeof(dsi->pdata->clk_config));
> > +
> > +	for (i = 0; i < ARRAY_SIZE(dsi->pdata->clk_config); i++) {
> > +		if (!dsi->clk_config[i].present)
> > +			continue;
> > +
> > +		clk_id = dsi->clk_config[i].id;
> > +		clk = devm_clk_get(dsi->dev, clk_id);
> > +		if (IS_ERR(clk)) {
> > +			ret = PTR_ERR(clk);
> > +			dev_err(dsi->dev, "Failed to get %s clock (%d)\n",
> > +				clk_id, ret);
> > +			return ret;
> > +		}
> > +		DRM_DEV_DEBUG_DRIVER(dsi->dev, "Setup clk %s (rate: %lu)\n",
> > +				     clk_id, clk_get_rate(clk));
> > +		dsi->clk_config[i].clk = clk;
> > +	}
> > +
> > +	/* DSI clocks */
> > +	clk = devm_clk_get(dsi->dev, "phy_ref");
> > +	if (IS_ERR(clk)) {
> > +		ret = PTR_ERR(clk);
> > +		dev_err(dsi->dev, "Failed to get phy_ref clock: %d\n", ret);
> > +		return ret;
> > +	}
> > +	dsi->phy_ref_clk = clk;
> > +
> > +	clk = devm_clk_get(dsi->dev, "rx_esc");
> > +	if (IS_ERR(clk)) {
> > +		ret = PTR_ERR(clk);
> > +		dev_err(dsi->dev, "Failed to get rx_esc clock: %d\n", ret);
> > +		return ret;
> > +	}
> > +	dsi->rx_esc_clk = clk;
> > +
> > +	clk = devm_clk_get(dsi->dev, "tx_esc");
> > +	if (IS_ERR(clk)) {
> > +		ret = PTR_ERR(clk);
> > +		dev_err(dsi->dev, "Failed to get tx_esc clock: %d\n", ret);
> > +		return ret;
> > +	}
> > +	dsi->tx_esc_clk = clk;
> > +
> > +	dsi->csr = syscon_regmap_lookup_by_phandle(np, "csr");
> > +	if (IS_ERR(dsi->csr) && dsi->pdata->ext_regs & IMX_REG_CSR) {
> > +		ret = PTR_ERR(dsi->csr);
> > +		DRM_DEV_ERROR(dsi->dev, "Failed to get CSR regmap: %d\n",
> > +			      ret);
> > +		return ret;
> > +	}
> 
> This doesn't seem to be used anywhere.

That's true. i had it in for the imx8q*, dropped that (and some other
parts) until support for that soc is added.

> 
> > +	dsi->reset = syscon_regmap_lookup_by_phandle(np, "src");
> > +	if (IS_ERR(dsi->reset) && (dsi->pdata->ext_regs & IMX_REG_SRC)) {
> > +		ret = PTR_ERR(dsi->reset);
> > +		DRM_DEV_ERROR(dsi->dev, "Failed to get SRC regmap: %d\n",
> > +			      ret);
> > +		return ret;
> > +	}
> 
> Couldn't you model a reset controller in that syscon, and use the reset
> controller API here ? It would allow moving the i.MX-specific power on
> and off functions from this driver, making it more generic.

In fact the reset controller is already there, wired it up accordingly.

> 
> > +	dsi->mux_sel = syscon_regmap_lookup_by_phandle(np, "mux-sel");
> > +	if (IS_ERR(dsi->mux_sel) && (dsi->pdata->ext_regs & IMX_REG_GPR)) {
> > +		ret = PTR_ERR(dsi->mux_sel);
> > +		DRM_DEV_ERROR(dsi->dev, "Failed to get GPR regmap: %d\n",
> > +			      ret);
> > +		return ret;
> > +	}
> > +
> > +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +	base = devm_ioremap_resource(dsi->dev, res);
> 
> You can replace those two calls with devm_platform_ioremap_resource().

Done.

> 
> > +	if (IS_ERR(base))
> > +		return PTR_ERR(base);
> > +
> > +	dsi->regmap =
> > +		devm_regmap_init_mmio(dsi->dev, base, &nwl_dsi_regmap_config);
> > +	if (IS_ERR(dsi->regmap)) {
> > +		ret = PTR_ERR(dsi->regmap);
> > +		DRM_DEV_ERROR(dsi->dev,
> > +			      "Failed to create NWL DSI regmap: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	dsi->irq = platform_get_irq(pdev, 0);
> > +	if (dsi->irq < 0) {
> > +		DRM_DEV_ERROR(dsi->dev, "Failed to get device IRQ: %d\n",
> > +			      dsi->irq);
> > +		return dsi->irq;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static int imx8mq_dsi_poweron(struct imx_nwl_dsi *dsi)
> > +{
> > +	/* otherwise the display stays blank */
> > +	usleep_range(200, 300);
> > +
> > +	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, PCLK_RESET_N,
> > +			   PCLK_RESET_N);
> > +	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, ESC_RESET_N,
> > +			   ESC_RESET_N);
> > +	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, RESET_BYTE_N,
> > +			   RESET_BYTE_N);
> > +	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, DPI_RESET_N,
> > +			   DPI_RESET_N);
> > +
> > +	return 0;
> > +}
> > +
> > +static int imx8mq_dsi_poweroff(struct imx_nwl_dsi *dsi)
> > +{
> > +	if (USE_SRC_RESET_QUIRK(dsi->quirks))
> > +		return 0;
> > +
> > +	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, PCLK_RESET_N, 0);
> > +	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, ESC_RESET_N, 0);
> > +	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, RESET_BYTE_N, 0);
> > +	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, DPI_RESET_N, 0);
> > +	return 0;
> > +}
> > +
> > +static const struct drm_bridge_timings imx_nwl_timings = {
> > +	.input_bus_flags = DRM_BUS_FLAG_DE_LOW,
> > +};
> > +
> > +static struct imx_nwl_platform_data imx8mq_dev = {
> 
> This structure should be const, especially as it contains function
> pointers.

Done.

> 
> > +	.poweron = &imx8mq_dsi_poweron,
> > +	.poweroff = &imx8mq_dsi_poweroff,
> > +	.clk_config = {
> > +		{ .id = CLK_CORE,   .present = true },
> > +		{ .id = CLK_PIXEL,  .present = false },
> > +		{ .id = CLK_BYPASS, .present = false },
> > +	},
> > +	.ext_regs = IMX_REG_SRC | IMX_REG_GPR,
> > +};
> > +
> > +static const struct of_device_id imx_nwl_dsi_dt_ids[] = {
> > +	{ .compatible = "fsl,imx8mq-nwl-dsi", .data = &imx8mq_dev, },
> > +	{ /* sentinel */ }
> > +};
> > +MODULE_DEVICE_TABLE(of, imx_nwl_dsi_dt_ids);
> > +
> > +static const struct soc_device_attribute imx_nwl_quirks_match[] = {
> > +	{ .soc_id = "i.MX8MQ", .revision = "2.0",
> > +	  .data = (void *)(E11418_HS_MODE_QUIRK | SRC_RESET_QUIRK) },
> > +	{ /* sentinel. */ },
> > +};
> > +
> > +static int imx_nwl_dsi_probe(struct platform_device *pdev)
> > +{
> > +	struct device *dev = &pdev->dev;
> > +	const struct of_device_id *of_id =
> > +		of_match_device(imx_nwl_dsi_dt_ids, dev);
> > +	const struct imx_nwl_platform_data *pdata = of_id->data;
> > +	const struct soc_device_attribute *attr;
> > +	struct imx_nwl_dsi *dsi;
> > +	int ret;
> > +
> > +	dsi = devm_kzalloc(dev, sizeof(*dsi), GFP_KERNEL);
> > +	if (!dsi)
> > +		return -ENOMEM;
> > +
> > +	dsi->dev = dev;
> > +	dsi->pdata = pdata;
> > +	dsi->dpms_mode = DRM_MODE_DPMS_OFF;
> 
> DPMS is legacy, let's not use it within the driver.

Removed that since the drm layer keeps the state for us.

> > +
> > +	ret = imx_nwl_dsi_parse_dt(dsi);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = devm_request_irq(dev, dsi->irq, nwl_dsi_irq_handler, 0,
> > +			       dev_name(dev), dsi);
> > +	if (ret < 0) {
> > +		DRM_DEV_ERROR(dev, "Failed to request IRQ: %d (%d)\n", dsi->irq,
> > +			      ret);
> > +		return ret;
> > +	}
> > +
> > +	dsi->dsi_host.ops = &nwl_dsi_host_ops;
> > +	dsi->dsi_host.dev = dev;
> > +	ret = mipi_dsi_host_register(&dsi->dsi_host);
> > +	if (ret) {
> > +		DRM_DEV_ERROR(dev, "Failed to register MIPI host: %d\n", ret);
> > +		goto err_cleanup;
> > +	}
> > +
> > +	attr = soc_device_match(imx_nwl_quirks_match);
> > +	if (attr)
> > +		dsi->quirks = (uintptr_t)attr->data;
> > +
> > +	dsi->bridge.driver_private = dsi;
> > +	dsi->bridge.funcs = &imx_nwl_dsi_bridge_funcs;
> > +	dsi->bridge.of_node = dev->of_node;
> > +	dsi->bridge.timings = &imx_nwl_timings;
> > +
> > +	drm_bridge_add(&dsi->bridge);
> > +
> > +	dev_set_drvdata(dev, dsi);
> > +	pm_runtime_enable(dev);
> > +	return 0;
> > +
> > +err_cleanup:
> > +	devm_free_irq(dev, dsi->irq, dsi);
> > +	return ret;
> > +}
> > +
> > +static int imx_nwl_dsi_remove(struct platform_device *pdev)
> > +{
> > +	pm_runtime_disable(&pdev->dev);
> 
> You should call drm_bridge_remove() here, not in
> nwl_dsi_host_detach().

I opted to call `mipi_dsi_host_unregister(&dsi->dsi_host)` which would
keep the removal in `nwl_dsi_host_detach()` but would also make sure
it's called on removal (modelled like cdns-dsi).

> 
> > +	return 0;
> > +}
> > +
> > +static struct platform_driver imx_nwl_dsi_driver = {
> > +	.probe		= imx_nwl_dsi_probe,
> > +	.remove		= imx_nwl_dsi_remove,
> > +	.driver		= {
> > +		.of_match_table = imx_nwl_dsi_dt_ids,
> > +		.name	= DRV_NAME,
> > +	},
> > +};
> > +
> > +module_platform_driver(imx_nwl_dsi_driver);
> > +
> > +MODULE_AUTHOR("NXP Semiconductor");
> > +MODULE_AUTHOR("Purism SPC");
> > +MODULE_DESCRIPTION("i.MX8 Northwest Logic MIPI-DSI driver");
> > +MODULE_LICENSE("GPL"); /* GPLv2 or later */
> > diff --git a/drivers/gpu/drm/bridge/imx-nwl/nwl-drv.h b/drivers/gpu/drm/bridge/imx-nwl/nwl-drv.h
> > new file mode 100644
> > index 000000000000..a1e30c58b627
> > --- /dev/null
> > +++ b/drivers/gpu/drm/bridge/imx-nwl/nwl-drv.h
> > @@ -0,0 +1,72 @@
> > +/* SPDX-License-Identifier: GPL-2.0+ */
> > +/*
> > + * i.MX8 NWL MIPI DSI host driver
> > + *
> > + * Copyright (C) 2017 NXP
> > + * Copyright (C) 2019 Purism SPC
> > + */
> > +
> > +#ifndef __NWL_DRV_H__
> > +#define __NWL_DRV_H__
> > +
> > +#include <drm/drm_mipi_dsi.h>
> > +#include <linux/phy/phy.h>
> > +
> > +struct imx_nwl_platform_data;
> > +
> > +/* i.MX8 NWL quirks */
> > +/* i.MX8MQ errata E11418 */
> > +#define E11418_HS_MODE_QUIRK	    BIT(0)
> > +#define USE_E11418_HS_MODE_QUIRK(x) ((x) & E11418_HS_MODE_QUIRK)
> > +
> > +/* Skip DSI bits in SRC on disable to avoid blank display on enable */
> > +#define SRC_RESET_QUIRK		    BIT(1)
> > +#define USE_SRC_RESET_QUIRK(x)	    ((x) & SRC_RESET_QUIRK)
> 
> The USE_* macros are not shorter to type, so I would type out the &
> check explicitly.

Dropped.

> > +
> > +#define NWL_MAX_PLATFORM_CLOCKS 3
> > +struct imx_nwl_clk_config {
> > +	const char *id;
> > +	struct clk *clk;
> > +	bool present;
> > +	bool enabled;
> > +	u32 rate;
> > +};
> > +
> > +struct imx_nwl_dsi {
> > +	struct drm_bridge bridge;
> > +	struct mipi_dsi_host dsi_host;
> > +	struct drm_bridge *panel_bridge;
> > +	struct device *dev;
> > +	struct phy *phy;
> > +	union phy_configure_opts phy_cfg;
> > +	unsigned int quirks;
> > +
> > +	struct regmap *regmap;
> > +	int irq;
> > +
> > +	/* External registers */
> > +	struct regmap *csr;
> > +	struct regmap *mux_sel;
> > +	struct regmap *reset;
> > +
> > +	/* Platform dependent clocks */
> > +	struct imx_nwl_clk_config clk_config[3];
> 
> I would use NWL_MAX_PLATFORM_CLOCKS instead of 3 as
> imx_nwl_platform_data uses the macro.

That was an omission, fixed.

> 
> > +	/* DSI clocks */
> > +	struct clk *phy_ref_clk;
> > +	struct clk *rx_esc_clk;
> > +	struct clk *tx_esc_clk;
> > +
> > +	/* dsi lanes */
> > +	u32 lanes;
> > +	enum mipi_dsi_pixel_format format;
> > +	struct videomode vm;
> > +	unsigned long dsi_mode_flags;
> > +
> > +	int dpms_mode;
> > +
> > +	struct mipi_dsi_transfer *xfer;
> > +
> > +	const struct imx_nwl_platform_data *pdata;
> > +};
> > +
> > +#endif /* __NWL_DRV_H__ */
> > diff --git a/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.c b/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.c
> > new file mode 100644
> > index 000000000000..0e1463af162f
> > --- /dev/null
> > +++ b/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.c
> > @@ -0,0 +1,745 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * NWL DSI host driver
> > + *
> > + * Copyright (C) 2017 NXP
> > + * Copyright (C) 2019 Purism SPC
> > + */
> > +
> > +#include <asm/unaligned.h>
> > +#include <drm/drm_atomic_helper.h>
> > +#include <drm/drm_crtc_helper.h>
> > +#include <drm/drm_of.h>
> > +#include <drm/drm_panel.h>
> > +#include <drm/drm_print.h>
> > +#include <linux/clk.h>
> > +#include <linux/irq.h>
> > +#include <linux/regmap.h>
> > +#include <video/mipi_display.h>
> > +#include <video/videomode.h>
> > +
> > +#include "nwl-drv.h"
> > +#include "nwl-dsi.h"
> > +
> > +#define MIPI_FIFO_TIMEOUT msecs_to_jiffies(500)
> > +
> > +/* PKT reg bit manipulation */
> > +#define REG_MASK(e, s) (((1 << ((e) - (s) + 1)) - 1) << (s))
> > +#define REG_PUT(x, e, s) (((x) << (s)) & REG_MASK(e, s))
> > +#define REG_GET(x, e, s) (((x) & REG_MASK(e, s)) >> (s))
> 
> Let's not reinvent the wheel, linux/bits.h and linux/bitfield.h can be
> used instead.

Done.

> 
> > +
> > +/*
> > + * PKT_CONTROL format:
> > + * [15: 0] - word count
> > + * [17:16] - virtual channel
> > + * [23:18] - data type
> > + * [24]	   - LP or HS select (0 - LP, 1 - HS)
> > + * [25]	   - perform BTA after packet is sent
> > + * [26]	   - perform BTA only, no packet tx
> > + */
> > +#define WC(x)		REG_PUT((x), 15,  0)
> > +#define TX_VC(x)	REG_PUT((x), 17, 16)
> > +#define TX_DT(x)	REG_PUT((x), 23, 18)
> > +#define HS_SEL(x)	REG_PUT((x), 24, 24)
> > +#define BTA_TX(x)	REG_PUT((x), 25, 25)
> > +#define BTA_NO_TX(x)	REG_PUT((x), 26, 26)
> > +
> > +/*
> > + * RX_PKT_HEADER format:
> > + * [15: 0] - word count
> > + * [21:16] - data type
> > + * [23:22] - virtual channel
> > + */
> > +#define RX_DT(x) REG_GET((x), 21, 16)
> > +#define RX_VC(x) REG_GET((x), 23, 22)
> > +
> > +/*
> > + * DSI Video mode
> > + */
> > +#define VIDEO_MODE_BURST_MODE_WITH_SYNC_PULSES		0
> > +#define VIDEO_MODE_NON_BURST_MODE_WITH_SYNC_EVENTS	BIT(0)
> > +#define VIDEO_MODE_BURST_MODE				BIT(1)
> > +
> > +/*
> > + * DPI color coding
> > + */
> > +#define DPI_16_BIT_565_PACKED	0
> > +#define DPI_16_BIT_565_ALIGNED	1
> > +#define DPI_16_BIT_565_SHIFTED	2
> > +#define DPI_18_BIT_PACKED	3
> > +#define DPI_18_BIT_ALIGNED	4
> > +#define DPI_24_BIT		5
> > +
> > +/*
> > + * DPI Pixel format
> > + */
> > +#define PIXEL_FORMAT_16  0
> > +#define PIXEL_FORMAT_18  BIT(0)
> > +#define PIXEL_FORMAT_18L BIT(1)
> > +#define PIXEL_FORMAT_24  (BIT(0) | BIT(1))
> > +
> > +enum transfer_direction { DSI_PACKET_SEND, DSI_PACKET_RECEIVE };
> 
> Line breaks please.

Done.

> 
> > +
> > +struct mipi_dsi_transfer {
> 
> Let's not use such a generic name for a driver-specific structure. You
> should name is nwl_dsi_transfer.

Fixed.

> 
> > +	const struct mipi_dsi_msg *msg;
> > +	struct mipi_dsi_packet packet;
> > +	struct completion completed;
> > +
> > +	int status; /* status of transmission */
> > +	enum transfer_direction direction;
> > +	bool need_bta;
> > +	u8 cmd;
> > +	u16 rx_word_count;
> > +	size_t tx_len; /* bytes sent */
> > +	size_t rx_len; /* bytes received */
> > +};
> > +
> > +static inline int nwl_dsi_write(struct imx_nwl_dsi *dsi, unsigned int reg,
> > +				u32 val)
> > +{
> > +	int ret;
> > +
> > +	ret = regmap_write(dsi->regmap, reg, val);
> > +	if (ret < 0)
> > +		DRM_DEV_ERROR(dsi->dev,
> > +			      "Failed to write NWL DSI reg 0x%x: %d\n", reg,
> > +			      ret);
> > +	return ret;
> > +}
> > +
> > +static inline u32 nwl_dsi_read(struct imx_nwl_dsi *dsi, u32 reg)
> > +{
> > +	unsigned int val;
> > +	int ret;
> > +
> > +	ret = regmap_read(dsi->regmap, reg, &val);
> > +	if (ret < 0)
> > +		DRM_DEV_ERROR(dsi->dev, "Failed to read NWL DSI reg 0x%x: %d\n",
> > +			      reg, ret);
> > +
> > +	return val;
> 
> You're loosing the error...

Looking at other drivers they often just ignore the return value of
regmap_read. The places we use this can't do much to recover from errors
so i figured it'd be best to at least log it so it becomes debuggable
instead of just dropping it to the floor.

> > +}
> > +
> > +static u32 nwl_dsi_get_dpi_pixel_format(enum mipi_dsi_pixel_format format)
> > +{
> > +	switch (format) {
> > +	case MIPI_DSI_FMT_RGB565:
> > +		return PIXEL_FORMAT_16;
> > +	case MIPI_DSI_FMT_RGB666:
> > +		return PIXEL_FORMAT_18L;
> > +	case MIPI_DSI_FMT_RGB666_PACKED:
> > +		return PIXEL_FORMAT_18;
> > +	case MIPI_DSI_FMT_RGB888:
> > +		return PIXEL_FORMAT_24;
> > +	default:
> > +		return -EINVAL;
> > +	}
> > +}
> > +
> > +int nwl_dsi_get_dphy_params(struct imx_nwl_dsi *dsi,
> > +			    const struct drm_display_mode *mode,
> > +			    union phy_configure_opts *phy_opts)
> > +{
> > +	unsigned long rate;
> > +
> > +	if (dsi->lanes < 1 || dsi->lanes > 4)
> > +		return -EINVAL;
> > +
> > +	/*
> > +	 * So far the DPHY spec minimal timings work for both mixel
> > +	 * dphy and nwl dsi host
> > +	 */
> > +	phy_mipi_dphy_get_default_config(
> > +		mode->crtc_clock * 1000,
> > +		mipi_dsi_pixel_format_to_bpp(dsi->format), dsi->lanes,
> > +		&phy_opts->mipi_dphy);
> > +	rate = clk_get_rate(dsi->tx_esc_clk);
> > +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "LP clk is @%lu Hz\n", rate);
> > +	phy_opts->mipi_dphy.lp_clk_rate = rate;
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(nwl_dsi_get_dphy_params);
> 
> No need to export symbols, those fubctions are only meant to be called
> from within the same module.

Removed (also left overs when i had these in two modules).

> 
> > +
> > +#define PSEC_PER_SEC 1000000000000LL
> > +/*
> > + * ps2bc - Picoseconds to byte clock cycles
> > + */
> > +static u32 ps2bc(struct imx_nwl_dsi *dsi, unsigned long long ps)
> > +{
> > +	int bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
> > +
> > +	return DIV_ROUND_UP(ps * dsi->vm.pixelclock * bpp,
> > +			    dsi->lanes * 8 * PSEC_PER_SEC);
> > +}
> > +
> > +/**
> > + * ui2bc - UI time periods to byte clock cycles
> > + */
> > +static u32 ui2bc(struct imx_nwl_dsi *dsi, unsigned long long ui)
> > +{
> > +	int bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
> > +
> > +	return DIV_ROUND_UP(ui * dsi->lanes, dsi->vm.pixelclock * bpp);
> > +}
> > +
> > +#define USEC_PER_SEC 1000000L
> > +/*
> > + * us2bc - micro seconds to lp clock cycles
> > + */
> > +static u32 us2lp(u32 lp_clk_rate, unsigned long us)
> > +{
> > +	return DIV_ROUND_UP(us * lp_clk_rate, USEC_PER_SEC);
> > +}
> > +
> > +static int nwl_dsi_config_host(struct imx_nwl_dsi *dsi)
> > +{
> > +	u32 cycles;
> > +	struct phy_configure_opts_mipi_dphy *cfg = &dsi->phy_cfg.mipi_dphy;
> > +
> > +	if (dsi->lanes < 1 || dsi->lanes > 4)
> > +		return -EINVAL;
> > +
> > +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "DSI Lanes %d\n", dsi->lanes);
> > +	nwl_dsi_write(dsi, CFG_NUM_LANES, dsi->lanes - 1);
> > +
> > +	if (dsi->dsi_mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS) {
> > +		nwl_dsi_write(dsi, CFG_NONCONTINUOUS_CLK, 0x01);
> > +		nwl_dsi_write(dsi, CFG_AUTOINSERT_EOTP, 0x01);
> > +	} else {
> > +		nwl_dsi_write(dsi, CFG_NONCONTINUOUS_CLK, 0x00);
> > +		nwl_dsi_write(dsi, CFG_AUTOINSERT_EOTP, 0x00);
> > +	}
> > +
> > +	/* values in byte clock cycles */
> > +	cycles = ui2bc(dsi, cfg->clk_pre);
> > +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_t_pre: 0x%x\n", cycles);
> > +	nwl_dsi_write(dsi, CFG_T_PRE, cycles);
> > +	cycles = ps2bc(dsi, cfg->lpx + cfg->clk_prepare + cfg->clk_zero);
> > +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_tx_gap (pre): 0x%x\n", cycles);
> > +	cycles += ui2bc(dsi, cfg->clk_pre);
> > +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_tx_gap: 0x%x\n", cycles);
> > +	nwl_dsi_write(dsi, CFG_T_POST, cycles);
> > +	cycles = ps2bc(dsi, cfg->hs_exit);
> > +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_tx_gap: 0x%x\n", cycles);
> > +	nwl_dsi_write(dsi, CFG_TX_GAP, cycles);
> > +
> > +	nwl_dsi_write(dsi, CFG_EXTRA_CMDS_AFTER_EOTP, 0x01);
> > +	nwl_dsi_write(dsi, CFG_HTX_TO_COUNT, 0x00);
> > +	nwl_dsi_write(dsi, CFG_LRX_H_TO_COUNT, 0x00);
> > +	nwl_dsi_write(dsi, CFG_BTA_H_TO_COUNT, 0x00);
> > +	/* In LP clock cycles */
> > +	cycles = us2lp(cfg->lp_clk_rate, cfg->wakeup);
> > +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_twakeup: 0x%x\n", cycles);
> > +	nwl_dsi_write(dsi, CFG_TWAKEUP, cycles);
> > +
> > +	return 0;
> > +}
> > +
> > +static int nwl_dsi_config_dpi(struct imx_nwl_dsi *dsi)
> > +{
> > +	struct videomode *vm = &dsi->vm;
> > +	u32 color_format, mode;
> > +	bool burst_mode;
> > +
> > +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "hfront_porch = %d\n", vm->hfront_porch);
> > +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "hback_porch = %d\n", vm->hback_porch);
> > +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "hsync_len = %d\n", vm->hsync_len);
> > +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "hactive = %d\n", vm->hactive);
> > +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "vfront_porch = %d\n", vm->vfront_porch);
> > +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "vback_porch = %d\n", vm->vback_porch);
> > +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "vsync_len = %d\n", vm->vsync_len);
> > +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "vactive = %d\n", vm->vactive);
> > +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "clock = %lu kHz\n",
> > +			     vm->pixelclock / 1000);
> > +
> > +	color_format = nwl_dsi_get_dpi_pixel_format(dsi->format);
> > +	if (color_format < 0) {
> > +		DRM_DEV_ERROR(dsi->dev, "Invalid color format 0x%x\n",
> > +			      dsi->format);
> > +		return color_format;
> > +	}
> > +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "pixel fmt = %d\n", dsi->format);
> > +
> > +	nwl_dsi_write(dsi, INTERFACE_COLOR_CODING, DPI_24_BIT);
> > +	nwl_dsi_write(dsi, PIXEL_FORMAT, color_format);
> > +	/*
> > +	 * Adjusting input polarity based on the video mode results in
> > +	 * a black screen so always pick active low:
> > +	 */
> > +	nwl_dsi_write(dsi, VSYNC_POLARITY, VSYNC_POLARITY_ACTIVE_LOW);
> > +	nwl_dsi_write(dsi, HSYNC_POLARITY, HSYNC_POLARITY_ACTIVE_LOW);
> > +
> > +	burst_mode = (dsi->dsi_mode_flags & MIPI_DSI_MODE_VIDEO_BURST) &&
> > +		     !(dsi->dsi_mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE);
> > +
> > +	if (burst_mode) {
> > +		nwl_dsi_write(dsi, VIDEO_MODE, VIDEO_MODE_BURST_MODE);
> > +		nwl_dsi_write(dsi, PIXEL_FIFO_SEND_LEVEL, 256);
> > +	} else {
> > +		mode = ((dsi->dsi_mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE) ?
> > +				VIDEO_MODE_BURST_MODE_WITH_SYNC_PULSES :
> > +				VIDEO_MODE_NON_BURST_MODE_WITH_SYNC_EVENTS);
> > +		nwl_dsi_write(dsi, VIDEO_MODE, mode);
> > +		nwl_dsi_write(dsi, PIXEL_FIFO_SEND_LEVEL, vm->hactive);
> > +	}
> > +
> > +	nwl_dsi_write(dsi, HFP, vm->hfront_porch);
> > +	nwl_dsi_write(dsi, HBP, vm->hback_porch);
> > +	nwl_dsi_write(dsi, HSA, vm->hsync_len);
> > +
> > +	nwl_dsi_write(dsi, ENABLE_MULT_PKTS, 0x0);
> > +	nwl_dsi_write(dsi, BLLP_MODE, 0x1);
> > +	nwl_dsi_write(dsi, ENABLE_MULT_PKTS, 0x0);
> > +	nwl_dsi_write(dsi, USE_NULL_PKT_BLLP, 0x0);
> > +	nwl_dsi_write(dsi, VC, 0x0);
> > +
> > +	nwl_dsi_write(dsi, PIXEL_PAYLOAD_SIZE, vm->hactive);
> > +	nwl_dsi_write(dsi, VACTIVE, vm->vactive - 1);
> > +	nwl_dsi_write(dsi, VBP, vm->vback_porch);
> > +	nwl_dsi_write(dsi, VFP, vm->vfront_porch);
> > +
> > +	return 0;
> > +}
> > +
> > +static int nwl_dsi_enable_tx_clock(struct imx_nwl_dsi *dsi)
> > +{
> > +	struct device *dev = dsi->dev;
> > +	int ret;
> > +
> > +	ret = clk_prepare_enable(dsi->tx_esc_clk);
> > +	if (ret < 0) {
> > +		DRM_DEV_ERROR(dev, "Failed to enable tx_esc clk: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	DRM_DEV_DEBUG_DRIVER(dev, "Enabled tx_esc clk @%lu Hz\n",
> > +			     clk_get_rate(dsi->tx_esc_clk));
> > +	return 0;
> > +}
> > +
> > +static int nwl_dsi_enable_rx_clock(struct imx_nwl_dsi *dsi)
> > +{
> > +	struct device *dev = dsi->dev;
> > +	int ret;
> > +
> > +	ret = clk_prepare_enable(dsi->rx_esc_clk);
> > +	if (ret < 0) {
> > +		DRM_DEV_ERROR(dev, "Failed to enable rx_esc clk: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	DRM_DEV_DEBUG_DRIVER(dev, "Enabled rx_esc clk @%lu Hz\n",
> > +			     clk_get_rate(dsi->rx_esc_clk));
> > +	return 0;
> > +}
> > +
> > +static void nwl_dsi_init_interrupts(struct imx_nwl_dsi *dsi)
> > +{
> > +	u32 irq_enable;
> > +
> > +	nwl_dsi_write(dsi, IRQ_MASK, 0xffffffff);
> > +	nwl_dsi_write(dsi, IRQ_MASK2, 0x7);
> > +
> > +	irq_enable = ~(u32)(TX_PKT_DONE_MASK | RX_PKT_HDR_RCVD_MASK |
> > +			    TX_FIFO_OVFLW_MASK | HS_TX_TIMEOUT_MASK);
> > +
> > +	nwl_dsi_write(dsi, IRQ_MASK, irq_enable);
> > +}
> > +
> > +static int nwl_dsi_host_attach(struct mipi_dsi_host *dsi_host,
> > +			       struct mipi_dsi_device *device)
> > +{
> > +	struct imx_nwl_dsi *dsi =
> > +		container_of(dsi_host, struct imx_nwl_dsi, dsi_host);
> > +	struct device *dev = dsi->dev;
> > +	struct drm_bridge *bridge;
> > +	struct drm_panel *panel;
> > +	int ret;
> > +
> > +	DRM_DEV_INFO(dev, "lanes=%u, format=0x%x flags=0x%lx\n", device->lanes,
> > +		     device->format, device->mode_flags);
> > +
> > +	if (device->lanes < 1 || device->lanes > 4)
> > +		return -EINVAL;
> > +
> > +	dsi->lanes = device->lanes;
> > +	dsi->format = device->format;
> > +	dsi->dsi_mode_flags = device->mode_flags;
> > +
> > +	ret = drm_of_find_panel_or_bridge(dsi->dev->of_node, 1, 0, &panel,
> > +					  &bridge);
> > +	if (ret)
> > +		return ret;
> > +
> > +	if (panel) {
> > +		bridge = drm_panel_bridge_add(panel, DRM_MODE_CONNECTOR_DSI);
> > +		if (IS_ERR(bridge))
> > +			return PTR_ERR(bridge);
> > +	}
> > +
> > +	dsi->panel_bridge = bridge;
> > +	drm_bridge_add(&dsi->bridge);
> > +
> > +	return 0;
> > +}
> > +
> > +static int nwl_dsi_host_detach(struct mipi_dsi_host *dsi_host,
> > +			       struct mipi_dsi_device *device)
> > +{
> > +	struct imx_nwl_dsi *dsi =
> > +		container_of(dsi_host, struct imx_nwl_dsi, dsi_host);
> > +
> > +	drm_of_panel_bridge_remove(dsi->dev->of_node, 1, 0);
> > +	drm_bridge_remove(&dsi->bridge);
> > +
> > +	return 0;
> > +}
> > +
> > +static bool nwl_dsi_read_packet(struct imx_nwl_dsi *dsi, u32 status)
> > +{
> > +	struct device *dev = dsi->dev;
> > +	struct mipi_dsi_transfer *xfer = dsi->xfer;
> > +	u8 *payload = xfer->msg->rx_buf;
> > +	u32 val;
> > +	u16 word_count;
> > +	u8 channel;
> > +	u8 data_type;
> > +
> > +	xfer->status = 0;
> > +
> > +	if (xfer->rx_word_count == 0) {
> > +		if (!(status & RX_PKT_HDR_RCVD))
> > +			return false;
> > +		/* Get the RX header and parse it */
> > +		val = nwl_dsi_read(dsi, RX_PKT_HEADER);
> > +		word_count = WC(val);
> > +		channel = RX_VC(val);
> > +		data_type = RX_DT(val);
> > +
> > +		if (channel != xfer->msg->channel) {
> > +			DRM_DEV_ERROR(dev,
> > +				      "[%02X] Channel mismatch (%u != %u)\n",
> > +				      xfer->cmd, channel, xfer->msg->channel);
> > +			return true;
> > +		}
> > +
> > +		switch (data_type) {
> > +		case MIPI_DSI_RX_GENERIC_SHORT_READ_RESPONSE_2BYTE:
> > +			/* Fall through */
> > +		case MIPI_DSI_RX_DCS_SHORT_READ_RESPONSE_2BYTE:
> > +			if (xfer->msg->rx_len > 1) {
> > +				/* read second byte */
> > +				payload[1] = word_count >> 8;
> > +				++xfer->rx_len;
> > +			}
> > +			/* Fall through */
> > +		case MIPI_DSI_RX_GENERIC_SHORT_READ_RESPONSE_1BYTE:
> > +			/* Fall through */
> > +		case MIPI_DSI_RX_DCS_SHORT_READ_RESPONSE_1BYTE:
> > +			if (xfer->msg->rx_len > 0) {
> > +				/* read first byte */
> > +				payload[0] = word_count & 0xff;
> > +				++xfer->rx_len;
> > +			}
> > +			xfer->status = xfer->rx_len;
> > +			return true;
> > +		case MIPI_DSI_RX_ACKNOWLEDGE_AND_ERROR_REPORT:
> > +			word_count &= 0xff;
> > +			DRM_DEV_ERROR(dev, "[%02X] DSI error report: 0x%02x\n",
> > +				      xfer->cmd, word_count);
> > +			xfer->status = -EPROTO;
> > +			return true;
> > +		}
> > +
> > +		if (word_count > xfer->msg->rx_len) {
> > +			DRM_DEV_ERROR(
> > +				dev,
> > +				"[%02X] Receive buffer too small: %lu (< %u)\n",
> > +				xfer->cmd, xfer->msg->rx_len, word_count);
> > +			return true;
> > +		}
> > +
> > +		xfer->rx_word_count = word_count;
> > +	} else {
> > +		/* Set word_count from previous header read */
> > +		word_count = xfer->rx_word_count;
> > +	}
> > +
> > +	/* If RX payload is not yet received, wait for it */
> > +	if (!(status & RX_PKT_PAYLOAD_DATA_RCVD))
> > +		return false;
> > +
> > +	/* Read the RX payload */
> > +	while (word_count >= 4) {
> > +		val = nwl_dsi_read(dsi, RX_PAYLOAD);
> > +		payload[0] = (val >> 0) & 0xff;
> > +		payload[1] = (val >> 8) & 0xff;
> > +		payload[2] = (val >> 16) & 0xff;
> > +		payload[3] = (val >> 24) & 0xff;
> > +		payload += 4;
> > +		xfer->rx_len += 4;
> > +		word_count -= 4;
> > +	}
> > +
> > +	if (word_count > 0) {
> > +		val = nwl_dsi_read(dsi, RX_PAYLOAD);
> > +		switch (word_count) {
> > +		case 3:
> > +			payload[2] = (val >> 16) & 0xff;
> > +			++xfer->rx_len;
> > +			/* Fall through */
> > +		case 2:
> > +			payload[1] = (val >> 8) & 0xff;
> > +			++xfer->rx_len;
> > +			/* Fall through */
> > +		case 1:
> > +			payload[0] = (val >> 0) & 0xff;
> > +			++xfer->rx_len;
> > +			break;
> > +		}
> > +	}
> > +
> > +	xfer->status = xfer->rx_len;
> > +
> > +	return true;
> > +}
> > +
> > +static void nwl_dsi_finish_transmission(struct imx_nwl_dsi *dsi, u32 status)
> > +{
> > +	struct mipi_dsi_transfer *xfer = dsi->xfer;
> > +	bool end_packet = false;
> > +
> > +	if (!xfer)
> > +		return;
> > +
> > +	if (status & TX_FIFO_OVFLW) {
> > +		DRM_DEV_ERROR_RATELIMITED(dsi->dev, "tx fifo overflow\n");
> > +		return;
> > +	}
> > +
> > +	if (status & HS_TX_TIMEOUT) {
> > +		DRM_DEV_ERROR_RATELIMITED(dsi->dev, "HS tx timeout\n");
> > +		return;
> > +	}
> > +
> > +	if (xfer->direction == DSI_PACKET_SEND && status & TX_PKT_DONE) {
> > +		xfer->status = xfer->tx_len;
> > +		end_packet = true;
> > +	} else if (status & DPHY_DIRECTION &&
> > +		   ((status & (RX_PKT_HDR_RCVD | RX_PKT_PAYLOAD_DATA_RCVD)))) {
> > +		end_packet = nwl_dsi_read_packet(dsi, status);
> > +	}
> > +
> > +	if (end_packet)
> > +		complete(&xfer->completed);
> > +}
> > +
> > +static void nwl_dsi_begin_transmission(struct imx_nwl_dsi *dsi)
> > +{
> > +	struct mipi_dsi_transfer *xfer = dsi->xfer;
> > +	struct mipi_dsi_packet *pkt = &xfer->packet;
> > +	const u8 *payload;
> > +	size_t length;
> > +	u16 word_count;
> > +	u8 hs_mode;
> > +	u32 val;
> > +	u32 hs_workaround = 0;
> > +
> > +	/* Send the payload, if any */
> > +	length = pkt->payload_length;
> > +	payload = pkt->payload;
> > +
> > +	while (length >= 4) {
> > +		val = get_unaligned_le32(payload);
> 
> The framework doesn't guarantee the payload to be aligned on a multiple
> of 4 bytes ?

It does as far as i can tell, dropped.

> 
> > +		hs_workaround |= !(val & 0xFFFF00);
> > +		nwl_dsi_write(dsi, TX_PAYLOAD, val);
> > +		payload += 4;
> > +		length -= 4;
> > +	}
> > +	/* Send the rest of the payload */
> > +	val = 0;
> > +	switch (length) {
> > +	case 3:
> > +		val |= payload[2] << 16;
> > +		/* Fall through */
> > +	case 2:
> > +		val |= payload[1] << 8;
> > +		hs_workaround |= !(val & 0xFFFF00);
> > +		/* Fall through */
> > +	case 1:
> > +		val |= payload[0];
> > +		nwl_dsi_write(dsi, TX_PAYLOAD, val);
> > +		break;
> > +	}
> > +	xfer->tx_len = pkt->payload_length;
> > +
> > +	/*
> > +	 * Send the header
> > +	 * header[0] = Virtual Channel + Data Type
> > +	 * header[1] = Word Count LSB (LP) or first param (SP)
> > +	 * header[2] = Word Count MSB (LP) or second param (SP)
> > +	 */
> > +	word_count = pkt->header[1] | (pkt->header[2] << 8);
> > +	if ((hs_workaround && USE_E11418_HS_MODE_QUIRK(dsi->quirks))) {
> > +		DRM_DEV_DEBUG_DRIVER(dsi->dev,
> > +				     "Using hs mode workaround for cmd 0x%x\n",
> > +				     xfer->cmd);
> > +		hs_mode = 1;
> > +	} else {
> > +		hs_mode = (xfer->msg->flags & MIPI_DSI_MSG_USE_LPM) ? 0 : 1;
> > +	}
> > +	val = WC(word_count) |
> > +		TX_VC(xfer->msg->channel) |
> > +		TX_DT(xfer->msg->type) |
> > +		HS_SEL(hs_mode) |
> > +		BTA_TX(xfer->need_bta);
> > +	nwl_dsi_write(dsi, PKT_CONTROL, val);
> > +
> > +	/* Send packet command */
> > +	nwl_dsi_write(dsi, SEND_PACKET, 0x1);
> > +}
> > +
> > +static ssize_t nwl_dsi_host_transfer(struct mipi_dsi_host *dsi_host,
> > +				     const struct mipi_dsi_msg *msg)
> > +{
> > +	struct imx_nwl_dsi *dsi =
> > +		container_of(dsi_host, struct imx_nwl_dsi, dsi_host);
> > +	struct mipi_dsi_transfer xfer;
> > +	ssize_t ret = 0;
> > +
> > +	/* Create packet to be sent */
> > +	dsi->xfer = &xfer;
> > +	ret = mipi_dsi_create_packet(&xfer.packet, msg);
> > +	if (ret < 0) {
> > +		dsi->xfer = NULL;
> > +		return ret;
> > +	}
> > +
> > +	if ((msg->type & MIPI_DSI_GENERIC_READ_REQUEST_0_PARAM ||
> > +	     msg->type & MIPI_DSI_GENERIC_READ_REQUEST_1_PARAM ||
> > +	     msg->type & MIPI_DSI_GENERIC_READ_REQUEST_2_PARAM ||
> > +	     msg->type & MIPI_DSI_DCS_READ) &&
> > +	    msg->rx_len > 0 && msg->rx_buf != NULL)
> > +		xfer.direction = DSI_PACKET_RECEIVE;
> > +	else
> > +		xfer.direction = DSI_PACKET_SEND;
> > +
> > +	xfer.need_bta = (xfer.direction == DSI_PACKET_RECEIVE);
> > +	xfer.need_bta |= (msg->flags & MIPI_DSI_MSG_REQ_ACK) ? 1 : 0;
> > +	xfer.msg = msg;
> > +	xfer.status = -ETIMEDOUT;
> > +	xfer.rx_word_count = 0;
> > +	xfer.rx_len = 0;
> > +	xfer.cmd = 0x00;
> > +	if (msg->tx_len > 0)
> > +		xfer.cmd = ((u8 *)(msg->tx_buf))[0];
> > +	init_completion(&xfer.completed);
> > +
> > +	nwl_dsi_enable_rx_clock(dsi);
> > +
> > +	/* Initiate the DSI packet transmision */
> > +	nwl_dsi_begin_transmission(dsi);
> > +
> > +	if (!wait_for_completion_timeout(&xfer.completed, MIPI_FIFO_TIMEOUT)) {
> > +		DRM_DEV_ERROR(dsi_host->dev, "[%02X] DSI transfer timed out\n",
> > +			      xfer.cmd);
> > +		ret = -ETIMEDOUT;
> > +	} else {
> > +		ret = xfer.status;
> > +	}
> > +
> > +	clk_disable_unprepare(dsi->rx_esc_clk);
> > +
> > +	return ret;
> > +}
> > +
> > +const struct mipi_dsi_host_ops nwl_dsi_host_ops = {
> > +	.attach = nwl_dsi_host_attach,
> > +	.detach = nwl_dsi_host_detach,
> > +	.transfer = nwl_dsi_host_transfer,
> > +};
> > +
> > +irqreturn_t nwl_dsi_irq_handler(int irq, void *data)
> > +{
> > +	u32 irq_status;
> > +	struct imx_nwl_dsi *dsi = data;
> > +
> > +	irq_status = nwl_dsi_read(dsi, IRQ_STATUS);
> > +
> > +	if (irq_status & TX_PKT_DONE || irq_status & RX_PKT_HDR_RCVD ||
> > +	    irq_status & RX_PKT_PAYLOAD_DATA_RCVD)
> > +		nwl_dsi_finish_transmission(dsi, irq_status);
> > +
> > +	return IRQ_HANDLED;
> > +}
> > +EXPORT_SYMBOL_GPL(nwl_dsi_irq_handler);
> > +
> > +int nwl_dsi_enable(struct imx_nwl_dsi *dsi)
> > +{
> > +	struct device *dev = dsi->dev;
> > +	union phy_configure_opts *phy_cfg = &dsi->phy_cfg;
> > +	int ret;
> > +
> > +	if (!dsi->lanes) {
> > +		DRM_DEV_ERROR(dev, "Need DSI lanes: %d\n", dsi->lanes);
> > +		return -EINVAL;
> > +	}
> > +
> > +	ret = phy_init(dsi->phy);
> > +	if (ret < 0) {
> > +		DRM_DEV_ERROR(dev, "Failed to init DSI phy: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	ret = phy_configure(dsi->phy, phy_cfg);
> > +	if (ret < 0) {
> > +		DRM_DEV_ERROR(dev, "Failed to configure DSI phy: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	ret = nwl_dsi_enable_tx_clock(dsi);
> > +	if (ret < 0) {
> > +		DRM_DEV_ERROR(dev, "Failed to enable tx clock: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	ret = nwl_dsi_config_host(dsi);
> > +	if (ret < 0) {
> > +		DRM_DEV_ERROR(dev, "Failed to set up DSI: %d", ret);
> > +		return ret;
> > +	}
> > +
> > +	ret = nwl_dsi_config_dpi(dsi);
> > +	if (ret < 0) {
> > +		DRM_DEV_ERROR(dev, "Failed to set up DPI: %d", ret);
> > +		return ret;
> > +	}
> > +
> > +	ret = phy_power_on(dsi->phy);
> > +	if (ret < 0) {
> > +		DRM_DEV_ERROR(dev, "Failed to power on DPHY (%d)\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	nwl_dsi_init_interrupts(dsi);
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(nwl_dsi_enable);
> > +
> > +int nwl_dsi_disable(struct imx_nwl_dsi *dsi)
> > +{
> > +	struct device *dev = dsi->dev;
> > +
> > +	DRM_DEV_DEBUG_DRIVER(dev, "Disabling clocks and phy\n");
> > +
> > +	phy_power_off(dsi->phy);
> > +	phy_exit(dsi->phy);
> > +
> > +	/* Disabling the clock before the phy breaks enabling dsi again */
> > +	clk_disable_unprepare(dsi->tx_esc_clk);
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(nwl_dsi_disable);
> > diff --git a/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.h b/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.h
> > new file mode 100644
> > index 000000000000..7bcf804843e2
> > --- /dev/null
> > +++ b/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.h
> > @@ -0,0 +1,111 @@
> > +/* SPDX-License-Identifier: GPL-2.0+ */
> > +/*
> > + * i.MX8 NWL MIPI DSI host driver
> > + *
> > + * Copyright (C) 2017 NXP
> > + * Copyright (C) 2019 Purism SPC
> > + */
> > +#ifndef __NWL_DSI_H__
> > +#define __NWL_DSI_H__
> > +
> > +#include <drm/drm_mipi_dsi.h>
> > +
> > +/* DSI HOST registers */
> > +#define CFG_NUM_LANES			0x0
> 
> Some of the register names are quite prone to namespace clashes. I
> recommend prefixing them all with NWL_DSI_.

Done, also the defines in nwl-dsi.c.

> 
> > +#define CFG_NONCONTINUOUS_CLK		0x4
> > +#define CFG_T_PRE			0x8
> > +#define CFG_T_POST			0xc
> > +#define CFG_TX_GAP			0x10
> > +#define CFG_AUTOINSERT_EOTP		0x14
> > +#define CFG_EXTRA_CMDS_AFTER_EOTP	0x18
> > +#define CFG_HTX_TO_COUNT		0x1c
> > +#define CFG_LRX_H_TO_COUNT		0x20
> > +#define CFG_BTA_H_TO_COUNT		0x24
> > +#define CFG_TWAKEUP			0x28
> > +#define CFG_STATUS_OUT			0x2c
> > +#define RX_ERROR_STATUS			0x30
> > +
> > +/* DSI DPI registers */
> > +#define PIXEL_PAYLOAD_SIZE		0x200
> > +#define PIXEL_FIFO_SEND_LEVEL		0x204
> > +#define INTERFACE_COLOR_CODING		0x208
> > +#define PIXEL_FORMAT			0x20c
> > +#define VSYNC_POLARITY			0x210
> > +#define VSYNC_POLARITY_ACTIVE_LOW	0
> > +#define VSYNC_POLARITY_ACTIVE_HIGH	BIT(1)
> > +
> > +#define HSYNC_POLARITY			0x214
> > +#define HSYNC_POLARITY_ACTIVE_LOW	0
> > +#define HSYNC_POLARITY_ACTIVE_HIGH	BIT(1)
> > +
> > +#define VIDEO_MODE			0x218
> > +#define HFP				0x21c
> > +#define HBP				0x220
> > +#define HSA				0x224
> > +#define ENABLE_MULT_PKTS		0x228
> > +#define VBP				0x22c
> > +#define VFP				0x230
> > +#define BLLP_MODE			0x234
> > +#define USE_NULL_PKT_BLLP		0x238
> > +#define VACTIVE				0x23c
> > +#define VC				0x240
> > +
> > +/* DSI APB PKT control */
> > +#define TX_PAYLOAD			0x280
> > +#define PKT_CONTROL			0x284
> > +#define SEND_PACKET			0x288
> > +#define PKT_STATUS			0x28c
> > +#define PKT_FIFO_WR_LEVEL		0x290
> > +#define PKT_FIFO_RD_LEVEL		0x294
> > +#define RX_PAYLOAD			0x298
> > +#define RX_PKT_HEADER			0x29c
> > +
> > +/* DSI IRQ handling */
> > +#define IRQ_STATUS			0x2a0
> > +#define SM_NOT_IDLE			BIT(0)
> > +#define TX_PKT_DONE			BIT(1)
> > +#define DPHY_DIRECTION			BIT(2)
> > +#define TX_FIFO_OVFLW			BIT(3)
> > +#define TX_FIFO_UDFLW			BIT(4)
> > +#define RX_FIFO_OVFLW			BIT(5)
> > +#define RX_FIFO_UDFLW			BIT(6)
> > +#define RX_PKT_HDR_RCVD			BIT(7)
> > +#define RX_PKT_PAYLOAD_DATA_RCVD	BIT(8)
> > +#define BTA_TIMEOUT			BIT(29)
> > +#define LP_RX_TIMEOUT			BIT(30)
> > +#define HS_TX_TIMEOUT			BIT(31)
> > +
> > +#define IRQ_STATUS2			0x2a4
> > +#define SINGLE_BIT_ECC_ERR		BIT(0)
> > +#define MULTI_BIT_ECC_ERR		BIT(1)
> > +#define CRC_ERR				BIT(2)
> > +
> > +#define IRQ_MASK			0x2a8
> > +#define SM_NOT_IDLE_MASK		BIT(0)
> > +#define TX_PKT_DONE_MASK		BIT(1)
> > +#define DPHY_DIRECTION_MASK		BIT(2)
> > +#define TX_FIFO_OVFLW_MASK		BIT(3)
> > +#define TX_FIFO_UDFLW_MASK		BIT(4)
> > +#define RX_FIFO_OVFLW_MASK		BIT(5)
> > +#define RX_FIFO_UDFLW_MASK		BIT(6)
> > +#define RX_PKT_HDR_RCVD_MASK		BIT(7)
> > +#define RX_PKT_PAYLOAD_DATA_RCVD_MASK	BIT(8)
> > +#define BTA_TIMEOUT_MASK		BIT(29)
> > +#define LP_RX_TIMEOUT_MASK		BIT(30)
> > +#define HS_TX_TIMEOUT_MASK		BIT(31)
> > +
> > +#define IRQ_MASK2			0x2ac
> > +#define SINGLE_BIT_ECC_ERR_MASK		BIT(0)
> > +#define MULTI_BIT_ECC_ERR_MASK		BIT(1)
> > +#define CRC_ERR_MASK			BIT(2)
> > +
> > +extern const struct mipi_dsi_host_ops nwl_dsi_host_ops;
> > +
> > +irqreturn_t nwl_dsi_irq_handler(int irq, void *data);
> > +int nwl_dsi_enable(struct imx_nwl_dsi *dsi);
> > +int nwl_dsi_disable(struct imx_nwl_dsi *dsi);
> > +int nwl_dsi_get_dphy_params(struct imx_nwl_dsi *dsi,
> > +			    const struct drm_display_mode *mode,
> > +			    union phy_configure_opts *phy_opts);
> > +
> > +#endif /* __NWL_DSI_H__ */
> 
> -- 
> Regards,
> 
> Laurent Pinchart
> 

Cheers and thanks for having a look!
 -- Guido

Patch

diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
index a6eec908c43e..38c3145a7e57 100644
--- a/drivers/gpu/drm/bridge/Kconfig
+++ b/drivers/gpu/drm/bridge/Kconfig
@@ -152,6 +152,8 @@  source "drivers/gpu/drm/bridge/analogix/Kconfig"
 
 source "drivers/gpu/drm/bridge/adv7511/Kconfig"
 
+source "drivers/gpu/drm/bridge/imx-nwl/Kconfig"
+
 source "drivers/gpu/drm/bridge/synopsys/Kconfig"
 
 endmenu
diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
index 4934fcf5a6f8..904a9eb3a20a 100644
--- a/drivers/gpu/drm/bridge/Makefile
+++ b/drivers/gpu/drm/bridge/Makefile
@@ -16,4 +16,5 @@  obj-$(CONFIG_DRM_ANALOGIX_DP) += analogix/
 obj-$(CONFIG_DRM_I2C_ADV7511) += adv7511/
 obj-$(CONFIG_DRM_TI_SN65DSI86) += ti-sn65dsi86.o
 obj-$(CONFIG_DRM_TI_TFP410) += ti-tfp410.o
+obj-y += imx-nwl/
 obj-y += synopsys/
diff --git a/drivers/gpu/drm/bridge/imx-nwl/Kconfig b/drivers/gpu/drm/bridge/imx-nwl/Kconfig
new file mode 100644
index 000000000000..822dba1b380a
--- /dev/null
+++ b/drivers/gpu/drm/bridge/imx-nwl/Kconfig
@@ -0,0 +1,15 @@ 
+config DRM_IMX_NWL_DSI
+	tristate "Support for Northwest Logic MIPI DSI Host controller"
+	depends on DRM && (ARCH_MXC || ARCH_MULTIPLATFORM || COMPILE_TEST)
+	depends on COMMON_CLK
+	depends on OF && HAS_IOMEM
+	select DRM_KMS_HELPER
+	select DRM_MIPI_DSI
+	select DRM_PANEL_BRIDGE
+	select GENERIC_PHY_MIPI_DPHY
+	select MFD_SYSCON
+	select REGMAP_MMIO
+	help
+	  This enables the Northwest Logic MIPI DSI Host controller as
+	  found on NXP's i.MX8 Processors.
+
diff --git a/drivers/gpu/drm/bridge/imx-nwl/Makefile b/drivers/gpu/drm/bridge/imx-nwl/Makefile
new file mode 100644
index 000000000000..9fa63483da5b
--- /dev/null
+++ b/drivers/gpu/drm/bridge/imx-nwl/Makefile
@@ -0,0 +1,2 @@ 
+imx-nwl-objs := nwl-drv.o nwl-dsi.o
+obj-$(CONFIG_DRM_IMX_NWL_DSI) += imx-nwl.o
diff --git a/drivers/gpu/drm/bridge/imx-nwl/nwl-drv.c b/drivers/gpu/drm/bridge/imx-nwl/nwl-drv.c
new file mode 100644
index 000000000000..451f8f067c6f
--- /dev/null
+++ b/drivers/gpu/drm/bridge/imx-nwl/nwl-drv.c
@@ -0,0 +1,529 @@ 
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * i.MX8 NWL MIPI DSI host driver
+ *
+ * Copyright (C) 2017 NXP
+ * Copyright (C) 2019 Purism SPC
+ */
+
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_of.h>
+#include <drm/drm_panel.h>
+#include <drm/drm_print.h>
+#include <drm/drm_probe_helper.h>
+#include <linux/clk-provider.h>
+#include <linux/clk.h>
+#include <linux/component.h>
+#include <linux/gpio/consumer.h>
+#include <linux/irq.h>
+#include <linux/mfd/syscon.h>
+#include <linux/mfd/syscon/imx8mq-iomuxc-gpr.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/phy/phy.h>
+#include <linux/regmap.h>
+#include <linux/sys_soc.h>
+#include <video/videomode.h>
+
+#include "nwl-drv.h"
+#include "nwl-dsi.h"
+
+#define DRV_NAME "imx-nwl-dsi"
+
+/* 8MQ SRC specific registers */
+#define SRC_MIPIPHY_RCR	0x28
+#define RESET_BYTE_N	BIT(1)
+#define RESET_N		BIT(2)
+#define DPI_RESET_N	BIT(3)
+#define ESC_RESET_N	BIT(4)
+#define PCLK_RESET_N	BIT(5)
+
+/* Possible clocks */
+#define CLK_PIXEL	"pixel"
+#define CLK_CORE	"core"
+#define CLK_BYPASS	"bypass"
+
+enum imx_ext_regs {
+	IMX_REG_CSR = BIT(1),
+	IMX_REG_SRC = BIT(2),
+	IMX_REG_GPR = BIT(3),
+};
+
+static const struct regmap_config nwl_dsi_regmap_config = {
+	.reg_bits = 16,
+	.val_bits = 32,
+	.reg_stride = 4,
+	.max_register = IRQ_MASK2,
+	.name = DRV_NAME,
+};
+
+struct imx_nwl_platform_data {
+	int (*poweron)(struct imx_nwl_dsi *dsi);
+	int (*poweroff)(struct imx_nwl_dsi *dsi);
+	u32 ext_regs; /* required external registers */
+	struct imx_nwl_clk_config clk_config[NWL_MAX_PLATFORM_CLOCKS];
+};
+
+static inline struct imx_nwl_dsi *bridge_to_dsi(struct drm_bridge *bridge)
+{
+	return container_of(bridge, struct imx_nwl_dsi, bridge);
+}
+
+static void imx_nwl_dsi_set_clocks(struct imx_nwl_dsi *dsi, bool enable)
+{
+	struct device *dev = dsi->dev;
+	const char *id;
+	struct clk *clk;
+	unsigned long new_rate, cur_rate;
+	bool enabled;
+	size_t i;
+	int ret;
+
+	DRM_DEV_DEBUG_DRIVER(dev, "%sabling platform clocks",
+			     enable ? "en" : "dis");
+	for (i = 0; i < ARRAY_SIZE(dsi->pdata->clk_config); i++) {
+		if (!dsi->clk_config[i].present)
+			continue;
+		id = dsi->clk_config[i].id;
+		clk = dsi->clk_config[i].clk;
+		new_rate = dsi->clk_config[i].rate;
+		cur_rate = clk_get_rate(clk);
+		enabled = dsi->clk_config[i].enabled;
+
+		/* BYPASS clk must have the same rate as PHY_REF clk */
+		if (!strcmp(id, CLK_BYPASS))
+			new_rate = clk_get_rate(dsi->phy_ref_clk);
+
+		if (enable) {
+			if (enabled && new_rate != cur_rate)
+				clk_disable_unprepare(clk);
+			else if (enabled && new_rate == cur_rate)
+				continue;
+			if (new_rate > 0)
+				clk_set_rate(clk, new_rate);
+			ret = clk_prepare_enable(clk);
+			if (ret < 0) {
+				DRM_DEV_ERROR(dev, "Failed to enable clock %s",
+					      id);
+			}
+			dsi->clk_config[i].enabled = true;
+			cur_rate = clk_get_rate(clk);
+			DRM_DEV_DEBUG_DRIVER(
+				dev, "Enabled %s clk (rate: req=%lu act=%lu)\n",
+				id, new_rate, cur_rate);
+		} else if (enabled) {
+			clk_disable_unprepare(clk);
+			dsi->clk_config[i].enabled = false;
+			DRM_DEV_DEBUG_DRIVER(dev, "Disabled %s clk\n", id);
+		}
+	}
+}
+
+static void imx_nwl_dsi_enable(struct imx_nwl_dsi *dsi)
+{
+	struct device *dev = dsi->dev;
+	int ret;
+
+	imx_nwl_dsi_set_clocks(dsi, true);
+
+	ret = dsi->pdata->poweron(dsi);
+	if (ret < 0)
+		DRM_DEV_ERROR(dev, "Failed to power on DSI (%d)\n", ret);
+}
+
+static void imx_nwl_dsi_disable(struct imx_nwl_dsi *dsi)
+{
+	struct device *dev = dsi->dev;
+
+	if (dsi->dpms_mode != DRM_MODE_DPMS_ON)
+		return;
+
+	DRM_DEV_DEBUG_DRIVER(dev, "Disabling encoder");
+	dsi->pdata->poweroff(dsi);
+	imx_nwl_dsi_set_clocks(dsi, false);
+}
+
+static void imx_nwl_select_input_source(struct imx_nwl_dsi *dsi)
+{
+	struct device_node *remote;
+	u32 mux_val = IMX8MQ_GPR13_MIPI_MUX_SEL;
+
+	remote = of_graph_get_remote_node(dsi->dev->of_node, 0, 0);
+	if (strcmp(remote->name, "lcdif") == 0)
+		mux_val = 0;
+
+	DRM_DEV_INFO(dsi->dev, "Using %s as input source\n",
+		     (mux_val) ? "DCSS" : "LCDIF");
+	regmap_update_bits(dsi->mux_sel, IOMUXC_GPR13,
+			   IMX8MQ_GPR13_MIPI_MUX_SEL, mux_val);
+	of_node_put(remote);
+}
+
+static void imx_nwl_dsi_bridge_disable(struct drm_bridge *bridge)
+{
+	struct imx_nwl_dsi *dsi = bridge_to_dsi(bridge);
+
+	if (dsi->dpms_mode != DRM_MODE_DPMS_ON)
+		return;
+
+	nwl_dsi_disable(dsi);
+	imx_nwl_dsi_disable(dsi);
+	pm_runtime_put_sync(dsi->dev);
+	dsi->dpms_mode = DRM_MODE_DPMS_OFF;
+}
+
+static bool
+imx_nwl_dsi_bridge_mode_fixup(struct drm_bridge *bridge,
+			      const struct drm_display_mode *mode,
+			      struct drm_display_mode *adjusted_mode)
+{
+	struct imx_nwl_dsi *dsi = bridge_to_dsi(bridge);
+	struct device *dev = dsi->dev;
+	union phy_configure_opts new_cfg;
+	unsigned long phy_ref_rate;
+	int ret;
+
+	ret = nwl_dsi_get_dphy_params(dsi, adjusted_mode, &new_cfg);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * If hs clock is unchanged, we're all good - all parameters are
+	 * derived from it atm.
+	 */
+	if (new_cfg.mipi_dphy.hs_clk_rate == dsi->phy_cfg.mipi_dphy.hs_clk_rate)
+		return true;
+
+	phy_ref_rate = clk_get_rate(dsi->phy_ref_clk);
+	DRM_DEV_DEBUG_DRIVER(dev, "PHY at ref rate: %lu\n", phy_ref_rate);
+	if (ret < 0) {
+		DRM_DEV_ERROR(dsi->dev,
+			      "Cannot setup PHY for mode: %ux%u @%d Hz\n",
+			      adjusted_mode->hdisplay, adjusted_mode->vdisplay,
+			      adjusted_mode->clock);
+		DRM_DEV_ERROR(dsi->dev, "PHY ref clk: %lu, bit clk: %lu\n",
+			      phy_ref_rate, new_cfg.mipi_dphy.hs_clk_rate);
+	} else {
+		/* Save the new desired phy config */
+		memcpy(&dsi->phy_cfg, &new_cfg, sizeof(new_cfg));
+	}
+
+	/* LCDIF + NWL needs active high sync */
+	adjusted_mode->flags |= (DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
+	adjusted_mode->flags &= ~(DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC);
+
+	drm_display_mode_to_videomode(adjusted_mode, &dsi->vm);
+	drm_mode_debug_printmodeline(adjusted_mode);
+
+	return ret == 0;
+}
+
+static enum drm_mode_status
+imx_nwl_dsi_bridge_mode_valid(struct drm_bridge *bridge,
+			      const struct drm_display_mode *mode)
+{
+	struct imx_nwl_dsi *dsi = bridge_to_dsi(bridge);
+	int bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
+
+	if (bpp < 0) {
+		DRM_DEV_ERROR(dsi->dev, "Invalid pixel format: %d\n",
+			      dsi->format);
+		return MODE_BAD;
+	}
+
+	return MODE_OK;
+}
+
+static void imx_nwl_dsi_bridge_pre_enable(struct drm_bridge *bridge)
+{
+	struct imx_nwl_dsi *dsi = bridge_to_dsi(bridge);
+
+	if (dsi->dpms_mode == DRM_MODE_DPMS_ON)
+		return;
+
+	imx_nwl_select_input_source(dsi);
+	pm_runtime_get_sync(dsi->dev);
+	imx_nwl_dsi_enable(dsi);
+	nwl_dsi_enable(dsi);
+	dsi->dpms_mode = DRM_MODE_DPMS_ON;
+}
+
+static int imx_nwl_dsi_bridge_attach(struct drm_bridge *bridge)
+{
+	struct imx_nwl_dsi *dsi = bridge->driver_private;
+	struct drm_encoder *encoder = bridge->encoder;
+
+	if (!encoder) {
+		DRM_DEV_ERROR(dsi->dev, "Parent encoder object not found\n");
+		return -ENODEV;
+	}
+
+	/* Set the encoder type as caller does not know it */
+	bridge->encoder->encoder_type = DRM_MODE_ENCODER_DSI;
+
+	/* Attach the panel-bridge to the dsi bridge */
+	return drm_bridge_attach(bridge->encoder, dsi->panel_bridge, bridge);
+}
+
+static void imx_nwl_dsi_bridge_detach(struct drm_bridge *bridge)
+{
+	struct imx_nwl_dsi *dsi = bridge->driver_private;
+
+	drm_of_panel_bridge_remove(dsi->dev->of_node, 1, 0);
+}
+
+/* see dw-mipi-dsi.c */
+static const struct drm_bridge_funcs imx_nwl_dsi_bridge_funcs = {
+	.pre_enable	= imx_nwl_dsi_bridge_pre_enable,
+	.disable    = imx_nwl_dsi_bridge_disable,
+	.mode_fixup = imx_nwl_dsi_bridge_mode_fixup,
+	.mode_valid = imx_nwl_dsi_bridge_mode_valid,
+	.attach	    = imx_nwl_dsi_bridge_attach,
+	.detach	    = imx_nwl_dsi_bridge_detach,
+};
+
+static int imx_nwl_dsi_parse_dt(struct imx_nwl_dsi *dsi)
+{
+	struct device_node *np = dsi->dev->of_node;
+	struct platform_device *pdev = to_platform_device(dsi->dev);
+	struct resource *res;
+	struct clk *clk;
+	const char *clk_id;
+	void __iomem *base;
+	int i, ret;
+
+	dsi->phy = devm_phy_get(dsi->dev, "dphy");
+	if (IS_ERR(dsi->phy)) {
+		ret = PTR_ERR(dsi->phy);
+		dev_err(dsi->dev, "Could not get PHY (%d)\n", ret);
+		return ret;
+	}
+
+	/* Platform dependent clocks */
+	memcpy(dsi->clk_config, dsi->pdata->clk_config,
+	       sizeof(dsi->pdata->clk_config));
+
+	for (i = 0; i < ARRAY_SIZE(dsi->pdata->clk_config); i++) {
+		if (!dsi->clk_config[i].present)
+			continue;
+
+		clk_id = dsi->clk_config[i].id;
+		clk = devm_clk_get(dsi->dev, clk_id);
+		if (IS_ERR(clk)) {
+			ret = PTR_ERR(clk);
+			dev_err(dsi->dev, "Failed to get %s clock (%d)\n",
+				clk_id, ret);
+			return ret;
+		}
+		DRM_DEV_DEBUG_DRIVER(dsi->dev, "Setup clk %s (rate: %lu)\n",
+				     clk_id, clk_get_rate(clk));
+		dsi->clk_config[i].clk = clk;
+	}
+
+	/* DSI clocks */
+	clk = devm_clk_get(dsi->dev, "phy_ref");
+	if (IS_ERR(clk)) {
+		ret = PTR_ERR(clk);
+		dev_err(dsi->dev, "Failed to get phy_ref clock: %d\n", ret);
+		return ret;
+	}
+	dsi->phy_ref_clk = clk;
+
+	clk = devm_clk_get(dsi->dev, "rx_esc");
+	if (IS_ERR(clk)) {
+		ret = PTR_ERR(clk);
+		dev_err(dsi->dev, "Failed to get rx_esc clock: %d\n", ret);
+		return ret;
+	}
+	dsi->rx_esc_clk = clk;
+
+	clk = devm_clk_get(dsi->dev, "tx_esc");
+	if (IS_ERR(clk)) {
+		ret = PTR_ERR(clk);
+		dev_err(dsi->dev, "Failed to get tx_esc clock: %d\n", ret);
+		return ret;
+	}
+	dsi->tx_esc_clk = clk;
+
+	dsi->csr = syscon_regmap_lookup_by_phandle(np, "csr");
+	if (IS_ERR(dsi->csr) && dsi->pdata->ext_regs & IMX_REG_CSR) {
+		ret = PTR_ERR(dsi->csr);
+		DRM_DEV_ERROR(dsi->dev, "Failed to get CSR regmap: %d\n",
+			      ret);
+		return ret;
+	}
+	dsi->reset = syscon_regmap_lookup_by_phandle(np, "src");
+	if (IS_ERR(dsi->reset) && (dsi->pdata->ext_regs & IMX_REG_SRC)) {
+		ret = PTR_ERR(dsi->reset);
+		DRM_DEV_ERROR(dsi->dev, "Failed to get SRC regmap: %d\n",
+			      ret);
+		return ret;
+	}
+	dsi->mux_sel = syscon_regmap_lookup_by_phandle(np, "mux-sel");
+	if (IS_ERR(dsi->mux_sel) && (dsi->pdata->ext_regs & IMX_REG_GPR)) {
+		ret = PTR_ERR(dsi->mux_sel);
+		DRM_DEV_ERROR(dsi->dev, "Failed to get GPR regmap: %d\n",
+			      ret);
+		return ret;
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base = devm_ioremap_resource(dsi->dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	dsi->regmap =
+		devm_regmap_init_mmio(dsi->dev, base, &nwl_dsi_regmap_config);
+	if (IS_ERR(dsi->regmap)) {
+		ret = PTR_ERR(dsi->regmap);
+		DRM_DEV_ERROR(dsi->dev,
+			      "Failed to create NWL DSI regmap: %d\n", ret);
+		return ret;
+	}
+
+	dsi->irq = platform_get_irq(pdev, 0);
+	if (dsi->irq < 0) {
+		DRM_DEV_ERROR(dsi->dev, "Failed to get device IRQ: %d\n",
+			      dsi->irq);
+		return dsi->irq;
+	}
+
+	return 0;
+}
+
+static int imx8mq_dsi_poweron(struct imx_nwl_dsi *dsi)
+{
+	/* otherwise the display stays blank */
+	usleep_range(200, 300);
+
+	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, PCLK_RESET_N,
+			   PCLK_RESET_N);
+	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, ESC_RESET_N,
+			   ESC_RESET_N);
+	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, RESET_BYTE_N,
+			   RESET_BYTE_N);
+	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, DPI_RESET_N,
+			   DPI_RESET_N);
+
+	return 0;
+}
+
+static int imx8mq_dsi_poweroff(struct imx_nwl_dsi *dsi)
+{
+	if (USE_SRC_RESET_QUIRK(dsi->quirks))
+		return 0;
+
+	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, PCLK_RESET_N, 0);
+	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, ESC_RESET_N, 0);
+	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, RESET_BYTE_N, 0);
+	regmap_update_bits(dsi->reset, SRC_MIPIPHY_RCR, DPI_RESET_N, 0);
+	return 0;
+}
+
+static const struct drm_bridge_timings imx_nwl_timings = {
+	.input_bus_flags = DRM_BUS_FLAG_DE_LOW,
+};
+
+static struct imx_nwl_platform_data imx8mq_dev = {
+	.poweron = &imx8mq_dsi_poweron,
+	.poweroff = &imx8mq_dsi_poweroff,
+	.clk_config = {
+		{ .id = CLK_CORE,   .present = true },
+		{ .id = CLK_PIXEL,  .present = false },
+		{ .id = CLK_BYPASS, .present = false },
+	},
+	.ext_regs = IMX_REG_SRC | IMX_REG_GPR,
+};
+
+static const struct of_device_id imx_nwl_dsi_dt_ids[] = {
+	{ .compatible = "fsl,imx8mq-nwl-dsi", .data = &imx8mq_dev, },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, imx_nwl_dsi_dt_ids);
+
+static const struct soc_device_attribute imx_nwl_quirks_match[] = {
+	{ .soc_id = "i.MX8MQ", .revision = "2.0",
+	  .data = (void *)(E11418_HS_MODE_QUIRK | SRC_RESET_QUIRK) },
+	{ /* sentinel. */ },
+};
+
+static int imx_nwl_dsi_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	const struct of_device_id *of_id =
+		of_match_device(imx_nwl_dsi_dt_ids, dev);
+	const struct imx_nwl_platform_data *pdata = of_id->data;
+	const struct soc_device_attribute *attr;
+	struct imx_nwl_dsi *dsi;
+	int ret;
+
+	dsi = devm_kzalloc(dev, sizeof(*dsi), GFP_KERNEL);
+	if (!dsi)
+		return -ENOMEM;
+
+	dsi->dev = dev;
+	dsi->pdata = pdata;
+	dsi->dpms_mode = DRM_MODE_DPMS_OFF;
+
+	ret = imx_nwl_dsi_parse_dt(dsi);
+	if (ret)
+		return ret;
+
+	ret = devm_request_irq(dev, dsi->irq, nwl_dsi_irq_handler, 0,
+			       dev_name(dev), dsi);
+	if (ret < 0) {
+		DRM_DEV_ERROR(dev, "Failed to request IRQ: %d (%d)\n", dsi->irq,
+			      ret);
+		return ret;
+	}
+
+	dsi->dsi_host.ops = &nwl_dsi_host_ops;
+	dsi->dsi_host.dev = dev;
+	ret = mipi_dsi_host_register(&dsi->dsi_host);
+	if (ret) {
+		DRM_DEV_ERROR(dev, "Failed to register MIPI host: %d\n", ret);
+		goto err_cleanup;
+	}
+
+	attr = soc_device_match(imx_nwl_quirks_match);
+	if (attr)
+		dsi->quirks = (uintptr_t)attr->data;
+
+	dsi->bridge.driver_private = dsi;
+	dsi->bridge.funcs = &imx_nwl_dsi_bridge_funcs;
+	dsi->bridge.of_node = dev->of_node;
+	dsi->bridge.timings = &imx_nwl_timings;
+
+	drm_bridge_add(&dsi->bridge);
+
+	dev_set_drvdata(dev, dsi);
+	pm_runtime_enable(dev);
+	return 0;
+
+err_cleanup:
+	devm_free_irq(dev, dsi->irq, dsi);
+	return ret;
+}
+
+static int imx_nwl_dsi_remove(struct platform_device *pdev)
+{
+	pm_runtime_disable(&pdev->dev);
+	return 0;
+}
+
+static struct platform_driver imx_nwl_dsi_driver = {
+	.probe		= imx_nwl_dsi_probe,
+	.remove		= imx_nwl_dsi_remove,
+	.driver		= {
+		.of_match_table = imx_nwl_dsi_dt_ids,
+		.name	= DRV_NAME,
+	},
+};
+
+module_platform_driver(imx_nwl_dsi_driver);
+
+MODULE_AUTHOR("NXP Semiconductor");
+MODULE_AUTHOR("Purism SPC");
+MODULE_DESCRIPTION("i.MX8 Northwest Logic MIPI-DSI driver");
+MODULE_LICENSE("GPL"); /* GPLv2 or later */
diff --git a/drivers/gpu/drm/bridge/imx-nwl/nwl-drv.h b/drivers/gpu/drm/bridge/imx-nwl/nwl-drv.h
new file mode 100644
index 000000000000..a1e30c58b627
--- /dev/null
+++ b/drivers/gpu/drm/bridge/imx-nwl/nwl-drv.h
@@ -0,0 +1,72 @@ 
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * i.MX8 NWL MIPI DSI host driver
+ *
+ * Copyright (C) 2017 NXP
+ * Copyright (C) 2019 Purism SPC
+ */
+
+#ifndef __NWL_DRV_H__
+#define __NWL_DRV_H__
+
+#include <drm/drm_mipi_dsi.h>
+#include <linux/phy/phy.h>
+
+struct imx_nwl_platform_data;
+
+/* i.MX8 NWL quirks */
+/* i.MX8MQ errata E11418 */
+#define E11418_HS_MODE_QUIRK	    BIT(0)
+#define USE_E11418_HS_MODE_QUIRK(x) ((x) & E11418_HS_MODE_QUIRK)
+
+/* Skip DSI bits in SRC on disable to avoid blank display on enable */
+#define SRC_RESET_QUIRK		    BIT(1)
+#define USE_SRC_RESET_QUIRK(x)	    ((x) & SRC_RESET_QUIRK)
+
+#define NWL_MAX_PLATFORM_CLOCKS 3
+struct imx_nwl_clk_config {
+	const char *id;
+	struct clk *clk;
+	bool present;
+	bool enabled;
+	u32 rate;
+};
+
+struct imx_nwl_dsi {
+	struct drm_bridge bridge;
+	struct mipi_dsi_host dsi_host;
+	struct drm_bridge *panel_bridge;
+	struct device *dev;
+	struct phy *phy;
+	union phy_configure_opts phy_cfg;
+	unsigned int quirks;
+
+	struct regmap *regmap;
+	int irq;
+
+	/* External registers */
+	struct regmap *csr;
+	struct regmap *mux_sel;
+	struct regmap *reset;
+
+	/* Platform dependent clocks */
+	struct imx_nwl_clk_config clk_config[3];
+	/* DSI clocks */
+	struct clk *phy_ref_clk;
+	struct clk *rx_esc_clk;
+	struct clk *tx_esc_clk;
+
+	/* dsi lanes */
+	u32 lanes;
+	enum mipi_dsi_pixel_format format;
+	struct videomode vm;
+	unsigned long dsi_mode_flags;
+
+	int dpms_mode;
+
+	struct mipi_dsi_transfer *xfer;
+
+	const struct imx_nwl_platform_data *pdata;
+};
+
+#endif /* __NWL_DRV_H__ */
diff --git a/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.c b/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.c
new file mode 100644
index 000000000000..0e1463af162f
--- /dev/null
+++ b/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.c
@@ -0,0 +1,745 @@ 
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * NWL DSI host driver
+ *
+ * Copyright (C) 2017 NXP
+ * Copyright (C) 2019 Purism SPC
+ */
+
+#include <asm/unaligned.h>
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_crtc_helper.h>
+#include <drm/drm_of.h>
+#include <drm/drm_panel.h>
+#include <drm/drm_print.h>
+#include <linux/clk.h>
+#include <linux/irq.h>
+#include <linux/regmap.h>
+#include <video/mipi_display.h>
+#include <video/videomode.h>
+
+#include "nwl-drv.h"
+#include "nwl-dsi.h"
+
+#define MIPI_FIFO_TIMEOUT msecs_to_jiffies(500)
+
+/* PKT reg bit manipulation */
+#define REG_MASK(e, s) (((1 << ((e) - (s) + 1)) - 1) << (s))
+#define REG_PUT(x, e, s) (((x) << (s)) & REG_MASK(e, s))
+#define REG_GET(x, e, s) (((x) & REG_MASK(e, s)) >> (s))
+
+/*
+ * PKT_CONTROL format:
+ * [15: 0] - word count
+ * [17:16] - virtual channel
+ * [23:18] - data type
+ * [24]	   - LP or HS select (0 - LP, 1 - HS)
+ * [25]	   - perform BTA after packet is sent
+ * [26]	   - perform BTA only, no packet tx
+ */
+#define WC(x)		REG_PUT((x), 15,  0)
+#define TX_VC(x)	REG_PUT((x), 17, 16)
+#define TX_DT(x)	REG_PUT((x), 23, 18)
+#define HS_SEL(x)	REG_PUT((x), 24, 24)
+#define BTA_TX(x)	REG_PUT((x), 25, 25)
+#define BTA_NO_TX(x)	REG_PUT((x), 26, 26)
+
+/*
+ * RX_PKT_HEADER format:
+ * [15: 0] - word count
+ * [21:16] - data type
+ * [23:22] - virtual channel
+ */
+#define RX_DT(x) REG_GET((x), 21, 16)
+#define RX_VC(x) REG_GET((x), 23, 22)
+
+/*
+ * DSI Video mode
+ */
+#define VIDEO_MODE_BURST_MODE_WITH_SYNC_PULSES		0
+#define VIDEO_MODE_NON_BURST_MODE_WITH_SYNC_EVENTS	BIT(0)
+#define VIDEO_MODE_BURST_MODE				BIT(1)
+
+/*
+ * DPI color coding
+ */
+#define DPI_16_BIT_565_PACKED	0
+#define DPI_16_BIT_565_ALIGNED	1
+#define DPI_16_BIT_565_SHIFTED	2
+#define DPI_18_BIT_PACKED	3
+#define DPI_18_BIT_ALIGNED	4
+#define DPI_24_BIT		5
+
+/*
+ * DPI Pixel format
+ */
+#define PIXEL_FORMAT_16  0
+#define PIXEL_FORMAT_18  BIT(0)
+#define PIXEL_FORMAT_18L BIT(1)
+#define PIXEL_FORMAT_24  (BIT(0) | BIT(1))
+
+enum transfer_direction { DSI_PACKET_SEND, DSI_PACKET_RECEIVE };
+
+struct mipi_dsi_transfer {
+	const struct mipi_dsi_msg *msg;
+	struct mipi_dsi_packet packet;
+	struct completion completed;
+
+	int status; /* status of transmission */
+	enum transfer_direction direction;
+	bool need_bta;
+	u8 cmd;
+	u16 rx_word_count;
+	size_t tx_len; /* bytes sent */
+	size_t rx_len; /* bytes received */
+};
+
+static inline int nwl_dsi_write(struct imx_nwl_dsi *dsi, unsigned int reg,
+				u32 val)
+{
+	int ret;
+
+	ret = regmap_write(dsi->regmap, reg, val);
+	if (ret < 0)
+		DRM_DEV_ERROR(dsi->dev,
+			      "Failed to write NWL DSI reg 0x%x: %d\n", reg,
+			      ret);
+	return ret;
+}
+
+static inline u32 nwl_dsi_read(struct imx_nwl_dsi *dsi, u32 reg)
+{
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read(dsi->regmap, reg, &val);
+	if (ret < 0)
+		DRM_DEV_ERROR(dsi->dev, "Failed to read NWL DSI reg 0x%x: %d\n",
+			      reg, ret);
+
+	return val;
+}
+
+static u32 nwl_dsi_get_dpi_pixel_format(enum mipi_dsi_pixel_format format)
+{
+	switch (format) {
+	case MIPI_DSI_FMT_RGB565:
+		return PIXEL_FORMAT_16;
+	case MIPI_DSI_FMT_RGB666:
+		return PIXEL_FORMAT_18L;
+	case MIPI_DSI_FMT_RGB666_PACKED:
+		return PIXEL_FORMAT_18;
+	case MIPI_DSI_FMT_RGB888:
+		return PIXEL_FORMAT_24;
+	default:
+		return -EINVAL;
+	}
+}
+
+int nwl_dsi_get_dphy_params(struct imx_nwl_dsi *dsi,
+			    const struct drm_display_mode *mode,
+			    union phy_configure_opts *phy_opts)
+{
+	unsigned long rate;
+
+	if (dsi->lanes < 1 || dsi->lanes > 4)
+		return -EINVAL;
+
+	/*
+	 * So far the DPHY spec minimal timings work for both mixel
+	 * dphy and nwl dsi host
+	 */
+	phy_mipi_dphy_get_default_config(
+		mode->crtc_clock * 1000,
+		mipi_dsi_pixel_format_to_bpp(dsi->format), dsi->lanes,
+		&phy_opts->mipi_dphy);
+	rate = clk_get_rate(dsi->tx_esc_clk);
+	DRM_DEV_DEBUG_DRIVER(dsi->dev, "LP clk is @%lu Hz\n", rate);
+	phy_opts->mipi_dphy.lp_clk_rate = rate;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nwl_dsi_get_dphy_params);
+
+#define PSEC_PER_SEC 1000000000000LL
+/*
+ * ps2bc - Picoseconds to byte clock cycles
+ */
+static u32 ps2bc(struct imx_nwl_dsi *dsi, unsigned long long ps)
+{
+	int bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
+
+	return DIV_ROUND_UP(ps * dsi->vm.pixelclock * bpp,
+			    dsi->lanes * 8 * PSEC_PER_SEC);
+}
+
+/**
+ * ui2bc - UI time periods to byte clock cycles
+ */
+static u32 ui2bc(struct imx_nwl_dsi *dsi, unsigned long long ui)
+{
+	int bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
+
+	return DIV_ROUND_UP(ui * dsi->lanes, dsi->vm.pixelclock * bpp);
+}
+
+#define USEC_PER_SEC 1000000L
+/*
+ * us2bc - micro seconds to lp clock cycles
+ */
+static u32 us2lp(u32 lp_clk_rate, unsigned long us)
+{
+	return DIV_ROUND_UP(us * lp_clk_rate, USEC_PER_SEC);
+}
+
+static int nwl_dsi_config_host(struct imx_nwl_dsi *dsi)
+{
+	u32 cycles;
+	struct phy_configure_opts_mipi_dphy *cfg = &dsi->phy_cfg.mipi_dphy;
+
+	if (dsi->lanes < 1 || dsi->lanes > 4)
+		return -EINVAL;
+
+	DRM_DEV_DEBUG_DRIVER(dsi->dev, "DSI Lanes %d\n", dsi->lanes);
+	nwl_dsi_write(dsi, CFG_NUM_LANES, dsi->lanes - 1);
+
+	if (dsi->dsi_mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS) {
+		nwl_dsi_write(dsi, CFG_NONCONTINUOUS_CLK, 0x01);
+		nwl_dsi_write(dsi, CFG_AUTOINSERT_EOTP, 0x01);
+	} else {
+		nwl_dsi_write(dsi, CFG_NONCONTINUOUS_CLK, 0x00);
+		nwl_dsi_write(dsi, CFG_AUTOINSERT_EOTP, 0x00);
+	}
+
+	/* values in byte clock cycles */
+	cycles = ui2bc(dsi, cfg->clk_pre);
+	DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_t_pre: 0x%x\n", cycles);
+	nwl_dsi_write(dsi, CFG_T_PRE, cycles);
+	cycles = ps2bc(dsi, cfg->lpx + cfg->clk_prepare + cfg->clk_zero);
+	DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_tx_gap (pre): 0x%x\n", cycles);
+	cycles += ui2bc(dsi, cfg->clk_pre);
+	DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_tx_gap: 0x%x\n", cycles);
+	nwl_dsi_write(dsi, CFG_T_POST, cycles);
+	cycles = ps2bc(dsi, cfg->hs_exit);
+	DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_tx_gap: 0x%x\n", cycles);
+	nwl_dsi_write(dsi, CFG_TX_GAP, cycles);
+
+	nwl_dsi_write(dsi, CFG_EXTRA_CMDS_AFTER_EOTP, 0x01);
+	nwl_dsi_write(dsi, CFG_HTX_TO_COUNT, 0x00);
+	nwl_dsi_write(dsi, CFG_LRX_H_TO_COUNT, 0x00);
+	nwl_dsi_write(dsi, CFG_BTA_H_TO_COUNT, 0x00);
+	/* In LP clock cycles */
+	cycles = us2lp(cfg->lp_clk_rate, cfg->wakeup);
+	DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_twakeup: 0x%x\n", cycles);
+	nwl_dsi_write(dsi, CFG_TWAKEUP, cycles);
+
+	return 0;
+}
+
+static int nwl_dsi_config_dpi(struct imx_nwl_dsi *dsi)
+{
+	struct videomode *vm = &dsi->vm;
+	u32 color_format, mode;
+	bool burst_mode;
+
+	DRM_DEV_DEBUG_DRIVER(dsi->dev, "hfront_porch = %d\n", vm->hfront_porch);
+	DRM_DEV_DEBUG_DRIVER(dsi->dev, "hback_porch = %d\n", vm->hback_porch);
+	DRM_DEV_DEBUG_DRIVER(dsi->dev, "hsync_len = %d\n", vm->hsync_len);
+	DRM_DEV_DEBUG_DRIVER(dsi->dev, "hactive = %d\n", vm->hactive);
+	DRM_DEV_DEBUG_DRIVER(dsi->dev, "vfront_porch = %d\n", vm->vfront_porch);
+	DRM_DEV_DEBUG_DRIVER(dsi->dev, "vback_porch = %d\n", vm->vback_porch);
+	DRM_DEV_DEBUG_DRIVER(dsi->dev, "vsync_len = %d\n", vm->vsync_len);
+	DRM_DEV_DEBUG_DRIVER(dsi->dev, "vactive = %d\n", vm->vactive);
+	DRM_DEV_DEBUG_DRIVER(dsi->dev, "clock = %lu kHz\n",
+			     vm->pixelclock / 1000);
+
+	color_format = nwl_dsi_get_dpi_pixel_format(dsi->format);
+	if (color_format < 0) {
+		DRM_DEV_ERROR(dsi->dev, "Invalid color format 0x%x\n",
+			      dsi->format);
+		return color_format;
+	}
+	DRM_DEV_DEBUG_DRIVER(dsi->dev, "pixel fmt = %d\n", dsi->format);
+
+	nwl_dsi_write(dsi, INTERFACE_COLOR_CODING, DPI_24_BIT);
+	nwl_dsi_write(dsi, PIXEL_FORMAT, color_format);
+	/*
+	 * Adjusting input polarity based on the video mode results in
+	 * a black screen so always pick active low:
+	 */
+	nwl_dsi_write(dsi, VSYNC_POLARITY, VSYNC_POLARITY_ACTIVE_LOW);
+	nwl_dsi_write(dsi, HSYNC_POLARITY, HSYNC_POLARITY_ACTIVE_LOW);
+
+	burst_mode = (dsi->dsi_mode_flags & MIPI_DSI_MODE_VIDEO_BURST) &&
+		     !(dsi->dsi_mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE);
+
+	if (burst_mode) {
+		nwl_dsi_write(dsi, VIDEO_MODE, VIDEO_MODE_BURST_MODE);
+		nwl_dsi_write(dsi, PIXEL_FIFO_SEND_LEVEL, 256);
+	} else {
+		mode = ((dsi->dsi_mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE) ?
+				VIDEO_MODE_BURST_MODE_WITH_SYNC_PULSES :
+				VIDEO_MODE_NON_BURST_MODE_WITH_SYNC_EVENTS);
+		nwl_dsi_write(dsi, VIDEO_MODE, mode);
+		nwl_dsi_write(dsi, PIXEL_FIFO_SEND_LEVEL, vm->hactive);
+	}
+
+	nwl_dsi_write(dsi, HFP, vm->hfront_porch);
+	nwl_dsi_write(dsi, HBP, vm->hback_porch);
+	nwl_dsi_write(dsi, HSA, vm->hsync_len);
+
+	nwl_dsi_write(dsi, ENABLE_MULT_PKTS, 0x0);
+	nwl_dsi_write(dsi, BLLP_MODE, 0x1);
+	nwl_dsi_write(dsi, ENABLE_MULT_PKTS, 0x0);
+	nwl_dsi_write(dsi, USE_NULL_PKT_BLLP, 0x0);
+	nwl_dsi_write(dsi, VC, 0x0);
+
+	nwl_dsi_write(dsi, PIXEL_PAYLOAD_SIZE, vm->hactive);
+	nwl_dsi_write(dsi, VACTIVE, vm->vactive - 1);
+	nwl_dsi_write(dsi, VBP, vm->vback_porch);
+	nwl_dsi_write(dsi, VFP, vm->vfront_porch);
+
+	return 0;
+}
+
+static int nwl_dsi_enable_tx_clock(struct imx_nwl_dsi *dsi)
+{
+	struct device *dev = dsi->dev;
+	int ret;
+
+	ret = clk_prepare_enable(dsi->tx_esc_clk);
+	if (ret < 0) {
+		DRM_DEV_ERROR(dev, "Failed to enable tx_esc clk: %d\n", ret);
+		return ret;
+	}
+
+	DRM_DEV_DEBUG_DRIVER(dev, "Enabled tx_esc clk @%lu Hz\n",
+			     clk_get_rate(dsi->tx_esc_clk));
+	return 0;
+}
+
+static int nwl_dsi_enable_rx_clock(struct imx_nwl_dsi *dsi)
+{
+	struct device *dev = dsi->dev;
+	int ret;
+
+	ret = clk_prepare_enable(dsi->rx_esc_clk);
+	if (ret < 0) {
+		DRM_DEV_ERROR(dev, "Failed to enable rx_esc clk: %d\n", ret);
+		return ret;
+	}
+
+	DRM_DEV_DEBUG_DRIVER(dev, "Enabled rx_esc clk @%lu Hz\n",
+			     clk_get_rate(dsi->rx_esc_clk));
+	return 0;
+}
+
+static void nwl_dsi_init_interrupts(struct imx_nwl_dsi *dsi)
+{
+	u32 irq_enable;
+
+	nwl_dsi_write(dsi, IRQ_MASK, 0xffffffff);
+	nwl_dsi_write(dsi, IRQ_MASK2, 0x7);
+
+	irq_enable = ~(u32)(TX_PKT_DONE_MASK | RX_PKT_HDR_RCVD_MASK |
+			    TX_FIFO_OVFLW_MASK | HS_TX_TIMEOUT_MASK);
+
+	nwl_dsi_write(dsi, IRQ_MASK, irq_enable);
+}
+
+static int nwl_dsi_host_attach(struct mipi_dsi_host *dsi_host,
+			       struct mipi_dsi_device *device)
+{
+	struct imx_nwl_dsi *dsi =
+		container_of(dsi_host, struct imx_nwl_dsi, dsi_host);
+	struct device *dev = dsi->dev;
+	struct drm_bridge *bridge;
+	struct drm_panel *panel;
+	int ret;
+
+	DRM_DEV_INFO(dev, "lanes=%u, format=0x%x flags=0x%lx\n", device->lanes,
+		     device->format, device->mode_flags);
+
+	if (device->lanes < 1 || device->lanes > 4)
+		return -EINVAL;
+
+	dsi->lanes = device->lanes;
+	dsi->format = device->format;
+	dsi->dsi_mode_flags = device->mode_flags;
+
+	ret = drm_of_find_panel_or_bridge(dsi->dev->of_node, 1, 0, &panel,
+					  &bridge);
+	if (ret)
+		return ret;
+
+	if (panel) {
+		bridge = drm_panel_bridge_add(panel, DRM_MODE_CONNECTOR_DSI);
+		if (IS_ERR(bridge))
+			return PTR_ERR(bridge);
+	}
+
+	dsi->panel_bridge = bridge;
+	drm_bridge_add(&dsi->bridge);
+
+	return 0;
+}
+
+static int nwl_dsi_host_detach(struct mipi_dsi_host *dsi_host,
+			       struct mipi_dsi_device *device)
+{
+	struct imx_nwl_dsi *dsi =
+		container_of(dsi_host, struct imx_nwl_dsi, dsi_host);
+
+	drm_of_panel_bridge_remove(dsi->dev->of_node, 1, 0);
+	drm_bridge_remove(&dsi->bridge);
+
+	return 0;
+}
+
+static bool nwl_dsi_read_packet(struct imx_nwl_dsi *dsi, u32 status)
+{
+	struct device *dev = dsi->dev;
+	struct mipi_dsi_transfer *xfer = dsi->xfer;
+	u8 *payload = xfer->msg->rx_buf;
+	u32 val;
+	u16 word_count;
+	u8 channel;
+	u8 data_type;
+
+	xfer->status = 0;
+
+	if (xfer->rx_word_count == 0) {
+		if (!(status & RX_PKT_HDR_RCVD))
+			return false;
+		/* Get the RX header and parse it */
+		val = nwl_dsi_read(dsi, RX_PKT_HEADER);
+		word_count = WC(val);
+		channel = RX_VC(val);
+		data_type = RX_DT(val);
+
+		if (channel != xfer->msg->channel) {
+			DRM_DEV_ERROR(dev,
+				      "[%02X] Channel mismatch (%u != %u)\n",
+				      xfer->cmd, channel, xfer->msg->channel);
+			return true;
+		}
+
+		switch (data_type) {
+		case MIPI_DSI_RX_GENERIC_SHORT_READ_RESPONSE_2BYTE:
+			/* Fall through */
+		case MIPI_DSI_RX_DCS_SHORT_READ_RESPONSE_2BYTE:
+			if (xfer->msg->rx_len > 1) {
+				/* read second byte */
+				payload[1] = word_count >> 8;
+				++xfer->rx_len;
+			}
+			/* Fall through */
+		case MIPI_DSI_RX_GENERIC_SHORT_READ_RESPONSE_1BYTE:
+			/* Fall through */
+		case MIPI_DSI_RX_DCS_SHORT_READ_RESPONSE_1BYTE:
+			if (xfer->msg->rx_len > 0) {
+				/* read first byte */
+				payload[0] = word_count & 0xff;
+				++xfer->rx_len;
+			}
+			xfer->status = xfer->rx_len;
+			return true;
+		case MIPI_DSI_RX_ACKNOWLEDGE_AND_ERROR_REPORT:
+			word_count &= 0xff;
+			DRM_DEV_ERROR(dev, "[%02X] DSI error report: 0x%02x\n",
+				      xfer->cmd, word_count);
+			xfer->status = -EPROTO;
+			return true;
+		}
+
+		if (word_count > xfer->msg->rx_len) {
+			DRM_DEV_ERROR(
+				dev,
+				"[%02X] Receive buffer too small: %lu (< %u)\n",
+				xfer->cmd, xfer->msg->rx_len, word_count);
+			return true;
+		}
+
+		xfer->rx_word_count = word_count;
+	} else {
+		/* Set word_count from previous header read */
+		word_count = xfer->rx_word_count;
+	}
+
+	/* If RX payload is not yet received, wait for it */
+	if (!(status & RX_PKT_PAYLOAD_DATA_RCVD))
+		return false;
+
+	/* Read the RX payload */
+	while (word_count >= 4) {
+		val = nwl_dsi_read(dsi, RX_PAYLOAD);
+		payload[0] = (val >> 0) & 0xff;
+		payload[1] = (val >> 8) & 0xff;
+		payload[2] = (val >> 16) & 0xff;
+		payload[3] = (val >> 24) & 0xff;
+		payload += 4;
+		xfer->rx_len += 4;
+		word_count -= 4;
+	}
+
+	if (word_count > 0) {
+		val = nwl_dsi_read(dsi, RX_PAYLOAD);
+		switch (word_count) {
+		case 3:
+			payload[2] = (val >> 16) & 0xff;
+			++xfer->rx_len;
+			/* Fall through */
+		case 2:
+			payload[1] = (val >> 8) & 0xff;
+			++xfer->rx_len;
+			/* Fall through */
+		case 1:
+			payload[0] = (val >> 0) & 0xff;
+			++xfer->rx_len;
+			break;
+		}
+	}
+
+	xfer->status = xfer->rx_len;
+
+	return true;
+}
+
+static void nwl_dsi_finish_transmission(struct imx_nwl_dsi *dsi, u32 status)
+{
+	struct mipi_dsi_transfer *xfer = dsi->xfer;
+	bool end_packet = false;
+
+	if (!xfer)
+		return;
+
+	if (status & TX_FIFO_OVFLW) {
+		DRM_DEV_ERROR_RATELIMITED(dsi->dev, "tx fifo overflow\n");
+		return;
+	}
+
+	if (status & HS_TX_TIMEOUT) {
+		DRM_DEV_ERROR_RATELIMITED(dsi->dev, "HS tx timeout\n");
+		return;
+	}
+
+	if (xfer->direction == DSI_PACKET_SEND && status & TX_PKT_DONE) {
+		xfer->status = xfer->tx_len;
+		end_packet = true;
+	} else if (status & DPHY_DIRECTION &&
+		   ((status & (RX_PKT_HDR_RCVD | RX_PKT_PAYLOAD_DATA_RCVD)))) {
+		end_packet = nwl_dsi_read_packet(dsi, status);
+	}
+
+	if (end_packet)
+		complete(&xfer->completed);
+}
+
+static void nwl_dsi_begin_transmission(struct imx_nwl_dsi *dsi)
+{
+	struct mipi_dsi_transfer *xfer = dsi->xfer;
+	struct mipi_dsi_packet *pkt = &xfer->packet;
+	const u8 *payload;
+	size_t length;
+	u16 word_count;
+	u8 hs_mode;
+	u32 val;
+	u32 hs_workaround = 0;
+
+	/* Send the payload, if any */
+	length = pkt->payload_length;
+	payload = pkt->payload;
+
+	while (length >= 4) {
+		val = get_unaligned_le32(payload);
+		hs_workaround |= !(val & 0xFFFF00);
+		nwl_dsi_write(dsi, TX_PAYLOAD, val);
+		payload += 4;
+		length -= 4;
+	}
+	/* Send the rest of the payload */
+	val = 0;
+	switch (length) {
+	case 3:
+		val |= payload[2] << 16;
+		/* Fall through */
+	case 2:
+		val |= payload[1] << 8;
+		hs_workaround |= !(val & 0xFFFF00);
+		/* Fall through */
+	case 1:
+		val |= payload[0];
+		nwl_dsi_write(dsi, TX_PAYLOAD, val);
+		break;
+	}
+	xfer->tx_len = pkt->payload_length;
+
+	/*
+	 * Send the header
+	 * header[0] = Virtual Channel + Data Type
+	 * header[1] = Word Count LSB (LP) or first param (SP)
+	 * header[2] = Word Count MSB (LP) or second param (SP)
+	 */
+	word_count = pkt->header[1] | (pkt->header[2] << 8);
+	if ((hs_workaround && USE_E11418_HS_MODE_QUIRK(dsi->quirks))) {
+		DRM_DEV_DEBUG_DRIVER(dsi->dev,
+				     "Using hs mode workaround for cmd 0x%x\n",
+				     xfer->cmd);
+		hs_mode = 1;
+	} else {
+		hs_mode = (xfer->msg->flags & MIPI_DSI_MSG_USE_LPM) ? 0 : 1;
+	}
+	val = WC(word_count) |
+		TX_VC(xfer->msg->channel) |
+		TX_DT(xfer->msg->type) |
+		HS_SEL(hs_mode) |
+		BTA_TX(xfer->need_bta);
+	nwl_dsi_write(dsi, PKT_CONTROL, val);
+
+	/* Send packet command */
+	nwl_dsi_write(dsi, SEND_PACKET, 0x1);
+}
+
+static ssize_t nwl_dsi_host_transfer(struct mipi_dsi_host *dsi_host,
+				     const struct mipi_dsi_msg *msg)
+{
+	struct imx_nwl_dsi *dsi =
+		container_of(dsi_host, struct imx_nwl_dsi, dsi_host);
+	struct mipi_dsi_transfer xfer;
+	ssize_t ret = 0;
+
+	/* Create packet to be sent */
+	dsi->xfer = &xfer;
+	ret = mipi_dsi_create_packet(&xfer.packet, msg);
+	if (ret < 0) {
+		dsi->xfer = NULL;
+		return ret;
+	}
+
+	if ((msg->type & MIPI_DSI_GENERIC_READ_REQUEST_0_PARAM ||
+	     msg->type & MIPI_DSI_GENERIC_READ_REQUEST_1_PARAM ||
+	     msg->type & MIPI_DSI_GENERIC_READ_REQUEST_2_PARAM ||
+	     msg->type & MIPI_DSI_DCS_READ) &&
+	    msg->rx_len > 0 && msg->rx_buf != NULL)
+		xfer.direction = DSI_PACKET_RECEIVE;
+	else
+		xfer.direction = DSI_PACKET_SEND;
+
+	xfer.need_bta = (xfer.direction == DSI_PACKET_RECEIVE);
+	xfer.need_bta |= (msg->flags & MIPI_DSI_MSG_REQ_ACK) ? 1 : 0;
+	xfer.msg = msg;
+	xfer.status = -ETIMEDOUT;
+	xfer.rx_word_count = 0;
+	xfer.rx_len = 0;
+	xfer.cmd = 0x00;
+	if (msg->tx_len > 0)
+		xfer.cmd = ((u8 *)(msg->tx_buf))[0];
+	init_completion(&xfer.completed);
+
+	nwl_dsi_enable_rx_clock(dsi);
+
+	/* Initiate the DSI packet transmision */
+	nwl_dsi_begin_transmission(dsi);
+
+	if (!wait_for_completion_timeout(&xfer.completed, MIPI_FIFO_TIMEOUT)) {
+		DRM_DEV_ERROR(dsi_host->dev, "[%02X] DSI transfer timed out\n",
+			      xfer.cmd);
+		ret = -ETIMEDOUT;
+	} else {
+		ret = xfer.status;
+	}
+
+	clk_disable_unprepare(dsi->rx_esc_clk);
+
+	return ret;
+}
+
+const struct mipi_dsi_host_ops nwl_dsi_host_ops = {
+	.attach = nwl_dsi_host_attach,
+	.detach = nwl_dsi_host_detach,
+	.transfer = nwl_dsi_host_transfer,
+};
+
+irqreturn_t nwl_dsi_irq_handler(int irq, void *data)
+{
+	u32 irq_status;
+	struct imx_nwl_dsi *dsi = data;
+
+	irq_status = nwl_dsi_read(dsi, IRQ_STATUS);
+
+	if (irq_status & TX_PKT_DONE || irq_status & RX_PKT_HDR_RCVD ||
+	    irq_status & RX_PKT_PAYLOAD_DATA_RCVD)
+		nwl_dsi_finish_transmission(dsi, irq_status);
+
+	return IRQ_HANDLED;
+}
+EXPORT_SYMBOL_GPL(nwl_dsi_irq_handler);
+
+int nwl_dsi_enable(struct imx_nwl_dsi *dsi)
+{
+	struct device *dev = dsi->dev;
+	union phy_configure_opts *phy_cfg = &dsi->phy_cfg;
+	int ret;
+
+	if (!dsi->lanes) {
+		DRM_DEV_ERROR(dev, "Need DSI lanes: %d\n", dsi->lanes);
+		return -EINVAL;
+	}
+
+	ret = phy_init(dsi->phy);
+	if (ret < 0) {
+		DRM_DEV_ERROR(dev, "Failed to init DSI phy: %d\n", ret);
+		return ret;
+	}
+
+	ret = phy_configure(dsi->phy, phy_cfg);
+	if (ret < 0) {
+		DRM_DEV_ERROR(dev, "Failed to configure DSI phy: %d\n", ret);
+		return ret;
+	}
+
+	ret = nwl_dsi_enable_tx_clock(dsi);
+	if (ret < 0) {
+		DRM_DEV_ERROR(dev, "Failed to enable tx clock: %d\n", ret);
+		return ret;
+	}
+
+	ret = nwl_dsi_config_host(dsi);
+	if (ret < 0) {
+		DRM_DEV_ERROR(dev, "Failed to set up DSI: %d", ret);
+		return ret;
+	}
+
+	ret = nwl_dsi_config_dpi(dsi);
+	if (ret < 0) {
+		DRM_DEV_ERROR(dev, "Failed to set up DPI: %d", ret);
+		return ret;
+	}
+
+	ret = phy_power_on(dsi->phy);
+	if (ret < 0) {
+		DRM_DEV_ERROR(dev, "Failed to power on DPHY (%d)\n", ret);
+		return ret;
+	}
+
+	nwl_dsi_init_interrupts(dsi);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nwl_dsi_enable);
+
+int nwl_dsi_disable(struct imx_nwl_dsi *dsi)
+{
+	struct device *dev = dsi->dev;
+
+	DRM_DEV_DEBUG_DRIVER(dev, "Disabling clocks and phy\n");
+
+	phy_power_off(dsi->phy);
+	phy_exit(dsi->phy);
+
+	/* Disabling the clock before the phy breaks enabling dsi again */
+	clk_disable_unprepare(dsi->tx_esc_clk);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nwl_dsi_disable);
diff --git a/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.h b/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.h
new file mode 100644
index 000000000000..7bcf804843e2
--- /dev/null
+++ b/drivers/gpu/drm/bridge/imx-nwl/nwl-dsi.h
@@ -0,0 +1,111 @@ 
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * i.MX8 NWL MIPI DSI host driver
+ *
+ * Copyright (C) 2017 NXP
+ * Copyright (C) 2019 Purism SPC
+ */
+#ifndef __NWL_DSI_H__
+#define __NWL_DSI_H__
+
+#include <drm/drm_mipi_dsi.h>
+
+/* DSI HOST registers */
+#define CFG_NUM_LANES			0x0
+#define CFG_NONCONTINUOUS_CLK		0x4
+#define CFG_T_PRE			0x8
+#define CFG_T_POST			0xc
+#define CFG_TX_GAP			0x10
+#define CFG_AUTOINSERT_EOTP		0x14
+#define CFG_EXTRA_CMDS_AFTER_EOTP	0x18
+#define CFG_HTX_TO_COUNT		0x1c
+#define CFG_LRX_H_TO_COUNT		0x20
+#define CFG_BTA_H_TO_COUNT		0x24
+#define CFG_TWAKEUP			0x28
+#define CFG_STATUS_OUT			0x2c
+#define RX_ERROR_STATUS			0x30
+
+/* DSI DPI registers */
+#define PIXEL_PAYLOAD_SIZE		0x200
+#define PIXEL_FIFO_SEND_LEVEL		0x204
+#define INTERFACE_COLOR_CODING		0x208
+#define PIXEL_FORMAT			0x20c
+#define VSYNC_POLARITY			0x210
+#define VSYNC_POLARITY_ACTIVE_LOW	0
+#define VSYNC_POLARITY_ACTIVE_HIGH	BIT(1)
+
+#define HSYNC_POLARITY			0x214
+#define HSYNC_POLARITY_ACTIVE_LOW	0
+#define HSYNC_POLARITY_ACTIVE_HIGH	BIT(1)
+
+#define VIDEO_MODE			0x218
+#define HFP				0x21c
+#define HBP				0x220
+#define HSA				0x224
+#define ENABLE_MULT_PKTS		0x228
+#define VBP				0x22c
+#define VFP				0x230
+#define BLLP_MODE			0x234
+#define USE_NULL_PKT_BLLP		0x238
+#define VACTIVE				0x23c
+#define VC				0x240
+
+/* DSI APB PKT control */
+#define TX_PAYLOAD			0x280
+#define PKT_CONTROL			0x284
+#define SEND_PACKET			0x288
+#define PKT_STATUS			0x28c
+#define PKT_FIFO_WR_LEVEL		0x290
+#define PKT_FIFO_RD_LEVEL		0x294
+#define RX_PAYLOAD			0x298
+#define RX_PKT_HEADER			0x29c
+
+/* DSI IRQ handling */
+#define IRQ_STATUS			0x2a0
+#define SM_NOT_IDLE			BIT(0)
+#define TX_PKT_DONE			BIT(1)
+#define DPHY_DIRECTION			BIT(2)
+#define TX_FIFO_OVFLW			BIT(3)
+#define TX_FIFO_UDFLW			BIT(4)
+#define RX_FIFO_OVFLW			BIT(5)
+#define RX_FIFO_UDFLW			BIT(6)
+#define RX_PKT_HDR_RCVD			BIT(7)
+#define RX_PKT_PAYLOAD_DATA_RCVD	BIT(8)
+#define BTA_TIMEOUT			BIT(29)
+#define LP_RX_TIMEOUT			BIT(30)
+#define HS_TX_TIMEOUT			BIT(31)
+
+#define IRQ_STATUS2			0x2a4
+#define SINGLE_BIT_ECC_ERR		BIT(0)
+#define MULTI_BIT_ECC_ERR		BIT(1)
+#define CRC_ERR				BIT(2)
+
+#define IRQ_MASK			0x2a8
+#define SM_NOT_IDLE_MASK		BIT(0)
+#define TX_PKT_DONE_MASK		BIT(1)
+#define DPHY_DIRECTION_MASK		BIT(2)
+#define TX_FIFO_OVFLW_MASK		BIT(3)
+#define TX_FIFO_UDFLW_MASK		BIT(4)
+#define RX_FIFO_OVFLW_MASK		BIT(5)
+#define RX_FIFO_UDFLW_MASK		BIT(6)
+#define RX_PKT_HDR_RCVD_MASK		BIT(7)
+#define RX_PKT_PAYLOAD_DATA_RCVD_MASK	BIT(8)
+#define BTA_TIMEOUT_MASK		BIT(29)
+#define LP_RX_TIMEOUT_MASK		BIT(30)
+#define HS_TX_TIMEOUT_MASK		BIT(31)
+
+#define IRQ_MASK2			0x2ac
+#define SINGLE_BIT_ECC_ERR_MASK		BIT(0)
+#define MULTI_BIT_ECC_ERR_MASK		BIT(1)
+#define CRC_ERR_MASK			BIT(2)
+
+extern const struct mipi_dsi_host_ops nwl_dsi_host_ops;
+
+irqreturn_t nwl_dsi_irq_handler(int irq, void *data);
+int nwl_dsi_enable(struct imx_nwl_dsi *dsi);
+int nwl_dsi_disable(struct imx_nwl_dsi *dsi);
+int nwl_dsi_get_dphy_params(struct imx_nwl_dsi *dsi,
+			    const struct drm_display_mode *mode,
+			    union phy_configure_opts *phy_opts);
+
+#endif /* __NWL_DSI_H__ */