diff mbox series

[v10,2/4] media: i2c: Add MAX9286 driver

Message ID 20200612144713.502006-3-kieran.bingham+renesas@ideasonboard.com (mailing list archive)
State New
Delegated to: Kieran Bingham
Headers show
Series MAX9286 GMSL Support (+RDACM20) | expand

Commit Message

Kieran Bingham June 12, 2020, 2:47 p.m. UTC
The MAX9286 is a 4-channel GMSL deserializer with coax or STP input and
CSI-2 output. The device supports multicamera streaming applications,
and features the ability to synchronise the attached cameras.

CSI-2 output can be configured with 1 to 4 lanes, and a control channel
is supported over I2C, which implements an I2C mux to facilitate
communications with connected cameras across the reverse control
channel.

Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

--
v2:
 - Fix MAINTAINERS entry

This posting is released with the following modifications to work
without Sakari's VC developments:
 - max9286_g_mbus_config() re-instated
 - max9286_get_frame_desc() is not bus/csi aware
 - max9286_{get,set}_routing() removed

v3:
 - Initialise notifier with v4l2_async_notifier_init
 - Update for new mbus csi2 format V4L2_MBUS_CSI2_DPHY

v4: - Re-introduce required code to function with the VC series.

 - Implement max9286_get_routing, max9286_set_routing
 - Remove max9286_g_mbus_config

v5: (internal release)
 - Fix printk formatting for hex value
 - max9286->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE (add |)
 - MEDIA_ENT_F_PROC_VIDEO_PIXEL_FORMATTER -> MEDIA_ENT_F_VID_IF_BRIDGE
 - Remove 'device is bound' workaround

v6:
 - v4l2_subdev_krouting instead of v4l2_subdev_routing separated
   to allow integration without the VC/V4L2-Mux series.
 - convert sd_to_max9286 to inline function
 - rename max9286_device to max9286_priv
 - Cleanup the v4l2_async_notifier
 - Extend MODULE_AUTHOR
 - Replace of_graph_get_endpoint_by_regs with fwnode_graph_get_endpoint_by_id
 - Pass default bus type when parsing fwnode endpoint (Manivannan Sadhasivam)
 - Use new YAML file reference in MAINTAINERS
 - Parse new i2c-mux node in max9286_get_i2c_by_id
   (This could/should be refactored to parse these separately first)
 - Spelling and calculation fixes in the FSYNC_LOCKED check comments
 - Identify each enabled i2c-mux channel in a single pass
 - max9286: Improve mux-state readbility [v2]
 - Fix frame sync lock durations
 - Add comment to describe /why/ we must open the mux in s_stream
 - use -EXDEV as return code for failed link synchronisation.
 - Fix reference counting of the dt nodeS
 - Convert to probe_new for I2C
 - Remove redundant max9286_i2c_mux_state
 - Provide optional enable-gpio (max9286-pwdn)

v7:
 [Kieran]
 - Ensure powerdown lines are optional
 - Add a 4ms power-up delay
 - Add max9286_check_config_link() to core
 - Add GPIO chip controller for GPIO0OUT and GPIO1OUT
 - Fix GPIO registration
 - max9286: Split out async registration
   (fixes regulator -EPROBE_DEFERs failures)
 - Collect all V4L2 registrations
 - balance v4l2_async refcnting
 - Rename max9286_v4l2_async_ => max9286_v4l2_notifier_

 [Jacopo]
 - Remove redundanct MAXIM_I2C_SPEED macros
 - Move notifiers operations
 - Add delay after reverse channel reconfiguration
 - Move link setup to completion
 - Fix up max9286_check_config_link() implementation
 - Remove redundant dual configuration of reverse channel

v8:

[Kieran]
 - Update the bound_sources mask on unbind
 - Convert probe kzalloc usage to devm_ variant
 - Fix up cleanup path from GPIO PowerDown registration
 - cleanup GPIO device registration fail path
 - Convert to use devm_regulator_get()
 - Fit max9286_parse_dt print on one line
 - Move multi-device workarounds out of upstream driver
 - Remove I2C mod-table
 - Lock format changes
 - Describe pad index usage
 - Remove poc_enabled workaround
 - Rename the max9286_gpio to be more explicit on it's actions.
 - Move max9286_init_format call
 - Rework probe sequence and simplify error paths.
 - Simplify i2c comments
 - Implement Pixelrate control
 - Disable overlap window

[Jacopo]
 - Adapt Kconfig to latest upstream changes
 - Put of node on error
 - Calculate pixel rate
 - Simplify overlap window disablement

v9:

[Kieran]
 - Kconfig: Depend on OF
 - Re-sort addition to Makefile

v10:

[Kieran]
 - Use the same default mbus_fmt everywhere
 - Don't provide GPIO names
 - Fix dev->of_node refcnting
 - Fix whitespace indent
 - Use single sample per pixel
 - Remove redundant DPHY check
 - Remove redundant v4l2_fwnode_endpoint_free call
 - Validate link formats
---
 MAINTAINERS                 |   10 +
 drivers/media/i2c/Kconfig   |   13 +
 drivers/media/i2c/Makefile  |    1 +
 drivers/media/i2c/max9286.c | 1320 +++++++++++++++++++++++++++++++++++
 4 files changed, 1344 insertions(+)
 create mode 100644 drivers/media/i2c/max9286.c

Comments

Manivannan Sadhasivam June 13, 2020, 7:09 a.m. UTC | #1
On Fri, Jun 12, 2020 at 03:47:11PM +0100, Kieran Bingham wrote:
> The MAX9286 is a 4-channel GMSL deserializer with coax or STP input and
> CSI-2 output. The device supports multicamera streaming applications,
> and features the ability to synchronise the attached cameras.
> 
> CSI-2 output can be configured with 1 to 4 lanes, and a control channel
> is supported over I2C, which implements an I2C mux to facilitate
> communications with connected cameras across the reverse control
> channel.
> 
> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Thanks,
Mani

> 
> --
> v2:
>  - Fix MAINTAINERS entry
> 
> This posting is released with the following modifications to work
> without Sakari's VC developments:
>  - max9286_g_mbus_config() re-instated
>  - max9286_get_frame_desc() is not bus/csi aware
>  - max9286_{get,set}_routing() removed
> 
> v3:
>  - Initialise notifier with v4l2_async_notifier_init
>  - Update for new mbus csi2 format V4L2_MBUS_CSI2_DPHY
> 
> v4: - Re-introduce required code to function with the VC series.
> 
>  - Implement max9286_get_routing, max9286_set_routing
>  - Remove max9286_g_mbus_config
> 
> v5: (internal release)
>  - Fix printk formatting for hex value
>  - max9286->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE (add |)
>  - MEDIA_ENT_F_PROC_VIDEO_PIXEL_FORMATTER -> MEDIA_ENT_F_VID_IF_BRIDGE
>  - Remove 'device is bound' workaround
> 
> v6:
>  - v4l2_subdev_krouting instead of v4l2_subdev_routing separated
>    to allow integration without the VC/V4L2-Mux series.
>  - convert sd_to_max9286 to inline function
>  - rename max9286_device to max9286_priv
>  - Cleanup the v4l2_async_notifier
>  - Extend MODULE_AUTHOR
>  - Replace of_graph_get_endpoint_by_regs with fwnode_graph_get_endpoint_by_id
>  - Pass default bus type when parsing fwnode endpoint (Manivannan Sadhasivam)
>  - Use new YAML file reference in MAINTAINERS
>  - Parse new i2c-mux node in max9286_get_i2c_by_id
>    (This could/should be refactored to parse these separately first)
>  - Spelling and calculation fixes in the FSYNC_LOCKED check comments
>  - Identify each enabled i2c-mux channel in a single pass
>  - max9286: Improve mux-state readbility [v2]
>  - Fix frame sync lock durations
>  - Add comment to describe /why/ we must open the mux in s_stream
>  - use -EXDEV as return code for failed link synchronisation.
>  - Fix reference counting of the dt nodeS
>  - Convert to probe_new for I2C
>  - Remove redundant max9286_i2c_mux_state
>  - Provide optional enable-gpio (max9286-pwdn)
> 
> v7:
>  [Kieran]
>  - Ensure powerdown lines are optional
>  - Add a 4ms power-up delay
>  - Add max9286_check_config_link() to core
>  - Add GPIO chip controller for GPIO0OUT and GPIO1OUT
>  - Fix GPIO registration
>  - max9286: Split out async registration
>    (fixes regulator -EPROBE_DEFERs failures)
>  - Collect all V4L2 registrations
>  - balance v4l2_async refcnting
>  - Rename max9286_v4l2_async_ => max9286_v4l2_notifier_
> 
>  [Jacopo]
>  - Remove redundanct MAXIM_I2C_SPEED macros
>  - Move notifiers operations
>  - Add delay after reverse channel reconfiguration
>  - Move link setup to completion
>  - Fix up max9286_check_config_link() implementation
>  - Remove redundant dual configuration of reverse channel
> 
> v8:
> 
> [Kieran]
>  - Update the bound_sources mask on unbind
>  - Convert probe kzalloc usage to devm_ variant
>  - Fix up cleanup path from GPIO PowerDown registration
>  - cleanup GPIO device registration fail path
>  - Convert to use devm_regulator_get()
>  - Fit max9286_parse_dt print on one line
>  - Move multi-device workarounds out of upstream driver
>  - Remove I2C mod-table
>  - Lock format changes
>  - Describe pad index usage
>  - Remove poc_enabled workaround
>  - Rename the max9286_gpio to be more explicit on it's actions.
>  - Move max9286_init_format call
>  - Rework probe sequence and simplify error paths.
>  - Simplify i2c comments
>  - Implement Pixelrate control
>  - Disable overlap window
> 
> [Jacopo]
>  - Adapt Kconfig to latest upstream changes
>  - Put of node on error
>  - Calculate pixel rate
>  - Simplify overlap window disablement
> 
> v9:
> 
> [Kieran]
>  - Kconfig: Depend on OF
>  - Re-sort addition to Makefile
> 
> v10:
> 
> [Kieran]
>  - Use the same default mbus_fmt everywhere
>  - Don't provide GPIO names
>  - Fix dev->of_node refcnting
>  - Fix whitespace indent
>  - Use single sample per pixel
>  - Remove redundant DPHY check
>  - Remove redundant v4l2_fwnode_endpoint_free call
>  - Validate link formats
> ---
>  MAINTAINERS                 |   10 +
>  drivers/media/i2c/Kconfig   |   13 +
>  drivers/media/i2c/Makefile  |    1 +
>  drivers/media/i2c/max9286.c | 1320 +++++++++++++++++++++++++++++++++++
>  4 files changed, 1344 insertions(+)
>  create mode 100644 drivers/media/i2c/max9286.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 791d2a862e41..7534df72033f 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -10274,6 +10274,16 @@ F:	Documentation/hwmon/max6697.rst
>  F:	drivers/hwmon/max6697.c
>  F:	include/linux/platform_data/max6697.h
>  
> +MAX9286 QUAD GMSL DESERIALIZER DRIVER
> +M:	Jacopo Mondi <jacopo+renesas@jmondi.org>
> +M:	Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> +M:	Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> +M:	Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> +L:	linux-media@vger.kernel.org
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
> +F:	drivers/media/i2c/max9286.c
> +
>  MAX9860 MONO AUDIO VOICE CODEC DRIVER
>  M:	Peter Rosin <peda@axentia.se>
>  L:	alsa-devel@alsa-project.org (moderated for non-subscribers)
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index da11036ad804..0a083407aa3e 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -464,6 +464,19 @@ config VIDEO_VPX3220
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called vpx3220.
>  
> +config VIDEO_MAX9286
> +	tristate "Maxim MAX9286 GMSL deserializer support"
> +	depends on I2C && I2C_MUX
> +	depends on OF
> +	select V4L2_FWNODE
> +	select VIDEO_V4L2_SUBDEV_API
> +	select MEDIA_CONTROLLER
> +	help
> +	  This driver supports the Maxim MAX9286 GMSL deserializer.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called max9286.
> +
>  comment "Video and audio decoders"
>  
>  config VIDEO_SAA717X
> diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
> index 993acab81b2c..c8010d77e1a3 100644
> --- a/drivers/media/i2c/Makefile
> +++ b/drivers/media/i2c/Makefile
> @@ -118,6 +118,7 @@ obj-$(CONFIG_VIDEO_IMX274)	+= imx274.o
>  obj-$(CONFIG_VIDEO_IMX290)	+= imx290.o
>  obj-$(CONFIG_VIDEO_IMX319)	+= imx319.o
>  obj-$(CONFIG_VIDEO_IMX355)	+= imx355.o
> +obj-$(CONFIG_VIDEO_MAX9286)	+= max9286.o
>  obj-$(CONFIG_VIDEO_ST_MIPID02) += st-mipid02.o
>  
>  obj-$(CONFIG_SDR_MAX2175) += max2175.o
> diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
> new file mode 100644
> index 000000000000..47f280518fdb
> --- /dev/null
> +++ b/drivers/media/i2c/max9286.c
> @@ -0,0 +1,1320 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Maxim MAX9286 GMSL Deserializer Driver
> + *
> + * Copyright (C) 2017-2019 Jacopo Mondi
> + * Copyright (C) 2017-2019 Kieran Bingham
> + * Copyright (C) 2017-2019 Laurent Pinchart
> + * Copyright (C) 2017-2019 Niklas Söderlund
> + * Copyright (C) 2016 Renesas Electronics Corporation
> + * Copyright (C) 2015 Cogent Embedded, Inc.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/fwnode.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/gpio/driver.h>
> +#include <linux/i2c.h>
> +#include <linux/i2c-mux.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/of_graph.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/slab.h>
> +
> +#include <media/v4l2-async.h>
> +#include <media/v4l2-ctrls.h>
> +#include <media/v4l2-device.h>
> +#include <media/v4l2-fwnode.h>
> +#include <media/v4l2-subdev.h>
> +
> +/* Register 0x00 */
> +#define MAX9286_MSTLINKSEL_AUTO		(7 << 5)
> +#define MAX9286_MSTLINKSEL(n)		((n) << 5)
> +#define MAX9286_EN_VS_GEN		BIT(4)
> +#define MAX9286_LINKEN(n)		(1 << (n))
> +/* Register 0x01 */
> +#define MAX9286_FSYNCMODE_ECU		(3 << 6)
> +#define MAX9286_FSYNCMODE_EXT		(2 << 6)
> +#define MAX9286_FSYNCMODE_INT_OUT	(1 << 6)
> +#define MAX9286_FSYNCMODE_INT_HIZ	(0 << 6)
> +#define MAX9286_GPIEN			BIT(5)
> +#define MAX9286_ENLMO_RSTFSYNC		BIT(2)
> +#define MAX9286_FSYNCMETH_AUTO		(2 << 0)
> +#define MAX9286_FSYNCMETH_SEMI_AUTO	(1 << 0)
> +#define MAX9286_FSYNCMETH_MANUAL	(0 << 0)
> +#define MAX9286_REG_FSYNC_PERIOD_L	0x06
> +#define MAX9286_REG_FSYNC_PERIOD_M	0x07
> +#define MAX9286_REG_FSYNC_PERIOD_H	0x08
> +/* Register 0x0a */
> +#define MAX9286_FWDCCEN(n)		(1 << ((n) + 4))
> +#define MAX9286_REVCCEN(n)		(1 << (n))
> +/* Register 0x0c */
> +#define MAX9286_HVEN			BIT(7)
> +#define MAX9286_EDC_6BIT_HAMMING	(2 << 5)
> +#define MAX9286_EDC_6BIT_CRC		(1 << 5)
> +#define MAX9286_EDC_1BIT_PARITY		(0 << 5)
> +#define MAX9286_DESEL			BIT(4)
> +#define MAX9286_INVVS			BIT(3)
> +#define MAX9286_INVHS			BIT(2)
> +#define MAX9286_HVSRC_D0		(2 << 0)
> +#define MAX9286_HVSRC_D14		(1 << 0)
> +#define MAX9286_HVSRC_D18		(0 << 0)
> +/* Register 0x0f */
> +#define MAX9286_0X0F_RESERVED		BIT(3)
> +/* Register 0x12 */
> +#define MAX9286_CSILANECNT(n)		(((n) - 1) << 6)
> +#define MAX9286_CSIDBL			BIT(5)
> +#define MAX9286_DBL			BIT(4)
> +#define MAX9286_DATATYPE_USER_8BIT	(11 << 0)
> +#define MAX9286_DATATYPE_USER_YUV_12BIT	(10 << 0)
> +#define MAX9286_DATATYPE_USER_24BIT	(9 << 0)
> +#define MAX9286_DATATYPE_RAW14		(8 << 0)
> +#define MAX9286_DATATYPE_RAW11		(7 << 0)
> +#define MAX9286_DATATYPE_RAW10		(6 << 0)
> +#define MAX9286_DATATYPE_RAW8		(5 << 0)
> +#define MAX9286_DATATYPE_YUV422_10BIT	(4 << 0)
> +#define MAX9286_DATATYPE_YUV422_8BIT	(3 << 0)
> +#define MAX9286_DATATYPE_RGB555		(2 << 0)
> +#define MAX9286_DATATYPE_RGB565		(1 << 0)
> +#define MAX9286_DATATYPE_RGB888		(0 << 0)
> +/* Register 0x15 */
> +#define MAX9286_VC(n)			((n) << 5)
> +#define MAX9286_VCTYPE			BIT(4)
> +#define MAX9286_CSIOUTEN		BIT(3)
> +#define MAX9286_0X15_RESV		(3 << 0)
> +/* Register 0x1b */
> +#define MAX9286_SWITCHIN(n)		(1 << ((n) + 4))
> +#define MAX9286_ENEQ(n)			(1 << (n))
> +/* Register 0x27 */
> +#define MAX9286_LOCKED			BIT(7)
> +/* Register 0x31 */
> +#define MAX9286_FSYNC_LOCKED		BIT(6)
> +/* Register 0x34 */
> +#define MAX9286_I2CLOCACK		BIT(7)
> +#define MAX9286_I2CSLVSH_1046NS_469NS	(3 << 5)
> +#define MAX9286_I2CSLVSH_938NS_352NS	(2 << 5)
> +#define MAX9286_I2CSLVSH_469NS_234NS	(1 << 5)
> +#define MAX9286_I2CSLVSH_352NS_117NS	(0 << 5)
> +#define MAX9286_I2CMSTBT_837KBPS	(7 << 2)
> +#define MAX9286_I2CMSTBT_533KBPS	(6 << 2)
> +#define MAX9286_I2CMSTBT_339KBPS	(5 << 2)
> +#define MAX9286_I2CMSTBT_173KBPS	(4 << 2)
> +#define MAX9286_I2CMSTBT_105KBPS	(3 << 2)
> +#define MAX9286_I2CMSTBT_84KBPS		(2 << 2)
> +#define MAX9286_I2CMSTBT_28KBPS		(1 << 2)
> +#define MAX9286_I2CMSTBT_8KBPS		(0 << 2)
> +#define MAX9286_I2CSLVTO_NONE		(3 << 0)
> +#define MAX9286_I2CSLVTO_1024US		(2 << 0)
> +#define MAX9286_I2CSLVTO_256US		(1 << 0)
> +#define MAX9286_I2CSLVTO_64US		(0 << 0)
> +/* Register 0x3b */
> +#define MAX9286_REV_TRF(n)		((n) << 4)
> +#define MAX9286_REV_AMP(n)		((((n) - 30) / 10) << 1) /* in mV */
> +#define MAX9286_REV_AMP_X		BIT(0)
> +/* Register 0x3f */
> +#define MAX9286_EN_REV_CFG		BIT(6)
> +#define MAX9286_REV_FLEN(n)		((n) - 20)
> +/* Register 0x49 */
> +#define MAX9286_VIDEO_DETECT_MASK	0x0f
> +/* Register 0x69 */
> +#define MAX9286_LFLTBMONMASKED		BIT(7)
> +#define MAX9286_LOCKMONMASKED		BIT(6)
> +#define MAX9286_AUTOCOMBACKEN		BIT(5)
> +#define MAX9286_AUTOMASKEN		BIT(4)
> +#define MAX9286_MASKLINK(n)		((n) << 0)
> +
> +/*
> + * The sink and source pads are created to match the OF graph port numbers so
> + * that their indexes can be used interchangeably.
> + */
> +#define MAX9286_NUM_GMSL		4
> +#define MAX9286_N_SINKS			4
> +#define MAX9286_N_PADS			5
> +#define MAX9286_SRC_PAD			4
> +
> +struct max9286_source {
> +	struct v4l2_async_subdev asd;
> +	struct v4l2_subdev *sd;
> +	struct fwnode_handle *fwnode;
> +};
> +
> +#define asd_to_max9286_source(_asd) \
> +	container_of(_asd, struct max9286_source, asd)
> +
> +struct max9286_priv {
> +	struct i2c_client *client;
> +	struct gpio_desc *gpiod_pwdn;
> +	struct v4l2_subdev sd;
> +	struct media_pad pads[MAX9286_N_PADS];
> +	struct regulator *regulator;
> +
> +	struct gpio_chip gpio;
> +	u8 gpio_state;
> +
> +	struct i2c_mux_core *mux;
> +	unsigned int mux_channel;
> +	bool mux_open;
> +
> +	struct v4l2_ctrl_handler ctrls;
> +	struct v4l2_ctrl *pixelrate;
> +
> +	struct v4l2_mbus_framefmt fmt[MAX9286_N_SINKS];
> +
> +	/* Protects controls and fmt structures */
> +	struct mutex mutex;
> +
> +	unsigned int nsources;
> +	unsigned int source_mask;
> +	unsigned int route_mask;
> +	unsigned int bound_sources;
> +	unsigned int csi2_data_lanes;
> +	struct max9286_source sources[MAX9286_NUM_GMSL];
> +	struct v4l2_async_notifier notifier;
> +};
> +
> +static struct max9286_source *next_source(struct max9286_priv *priv,
> +					  struct max9286_source *source)
> +{
> +	if (!source)
> +		source = &priv->sources[0];
> +	else
> +		source++;
> +
> +	for (; source < &priv->sources[MAX9286_NUM_GMSL]; source++) {
> +		if (source->fwnode)
> +			return source;
> +	}
> +
> +	return NULL;
> +}
> +
> +#define for_each_source(priv, source) \
> +	for ((source) = NULL; ((source) = next_source((priv), (source))); )
> +
> +#define to_index(priv, source) ((source) - &(priv)->sources[0])
> +
> +static inline struct max9286_priv *sd_to_max9286(struct v4l2_subdev *sd)
> +{
> +	return container_of(sd, struct max9286_priv, sd);
> +}
> +
> +/* -----------------------------------------------------------------------------
> + * I2C IO
> + */
> +
> +static int max9286_read(struct max9286_priv *priv, u8 reg)
> +{
> +	int ret;
> +
> +	ret = i2c_smbus_read_byte_data(priv->client, reg);
> +	if (ret < 0)
> +		dev_err(&priv->client->dev,
> +			"%s: register 0x%02x read failed (%d)\n",
> +			__func__, reg, ret);
> +
> +	return ret;
> +}
> +
> +static int max9286_write(struct max9286_priv *priv, u8 reg, u8 val)
> +{
> +	int ret;
> +
> +	ret = i2c_smbus_write_byte_data(priv->client, reg, val);
> +	if (ret < 0)
> +		dev_err(&priv->client->dev,
> +			"%s: register 0x%02x write failed (%d)\n",
> +			__func__, reg, ret);
> +
> +	return ret;
> +}
> +
> +/* -----------------------------------------------------------------------------
> + * I2C Multiplexer
> + */
> +
> +static void max9286_i2c_mux_configure(struct max9286_priv *priv, u8 conf)
> +{
> +	max9286_write(priv, 0x0a, conf);
> +
> +	/*
> +	 * We must sleep after any change to the forward or reverse channel
> +	 * configuration.
> +	 */
> +	usleep_range(3000, 5000);
> +}
> +
> +static void max9286_i2c_mux_open(struct max9286_priv *priv)
> +{
> +	/* Open all channels on the MAX9286 */
> +	max9286_i2c_mux_configure(priv, 0xff);
> +
> +	priv->mux_open = true;
> +}
> +
> +static void max9286_i2c_mux_close(struct max9286_priv *priv)
> +{
> +	/*
> +	 * Ensure that both the forward and reverse channel are disabled on the
> +	 * mux, and that the channel ID is invalidated to ensure we reconfigure
> +	 * on the next max9286_i2c_mux_select() call.
> +	 */
> +	max9286_i2c_mux_configure(priv, 0x00);
> +
> +	priv->mux_open = false;
> +	priv->mux_channel = -1;
> +}
> +
> +static int max9286_i2c_mux_select(struct i2c_mux_core *muxc, u32 chan)
> +{
> +	struct max9286_priv *priv = i2c_mux_priv(muxc);
> +
> +	/* Channel select is disabled when configured in the opened state. */
> +	if (priv->mux_open)
> +		return 0;
> +
> +	if (priv->mux_channel == chan)
> +		return 0;
> +
> +	priv->mux_channel = chan;
> +
> +	max9286_i2c_mux_configure(priv,
> +				  MAX9286_FWDCCEN(chan) |
> +				  MAX9286_REVCCEN(chan));
> +
> +	return 0;
> +}
> +
> +static int max9286_i2c_mux_init(struct max9286_priv *priv)
> +{
> +	struct max9286_source *source;
> +	int ret;
> +
> +	if (!i2c_check_functionality(priv->client->adapter,
> +				     I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
> +		return -ENODEV;
> +
> +	priv->mux = i2c_mux_alloc(priv->client->adapter, &priv->client->dev,
> +				  priv->nsources, 0, I2C_MUX_LOCKED,
> +				  max9286_i2c_mux_select, NULL);
> +	if (!priv->mux)
> +		return -ENOMEM;
> +
> +	priv->mux->priv = priv;
> +
> +	for_each_source(priv, source) {
> +		unsigned int index = to_index(priv, source);
> +
> +		ret = i2c_mux_add_adapter(priv->mux, 0, index, 0);
> +		if (ret < 0)
> +			goto error;
> +	}
> +
> +	return 0;
> +
> +error:
> +	i2c_mux_del_adapters(priv->mux);
> +	return ret;
> +}
> +
> +static void max9286_configure_i2c(struct max9286_priv *priv, bool localack)
> +{
> +	u8 config = MAX9286_I2CSLVSH_469NS_234NS | MAX9286_I2CSLVTO_1024US |
> +		    MAX9286_I2CMSTBT_105KBPS;
> +
> +	if (localack)
> +		config |= MAX9286_I2CLOCACK;
> +
> +	max9286_write(priv, 0x34, config);
> +	usleep_range(3000, 5000);
> +}
> +
> +/*
> + * max9286_check_video_links() - Make sure video links are detected and locked
> + *
> + * Performs safety checks on video link status. Make sure they are detected
> + * and all enabled links are locked.
> + *
> + * Returns 0 for success, -EIO for errors.
> + */
> +static int max9286_check_video_links(struct max9286_priv *priv)
> +{
> +	unsigned int i;
> +	int ret;
> +
> +	/*
> +	 * Make sure valid video links are detected.
> +	 * The delay is not characterized in de-serializer manual, wait up
> +	 * to 5 ms.
> +	 */
> +	for (i = 0; i < 10; i++) {
> +		ret = max9286_read(priv, 0x49);
> +		if (ret < 0)
> +			return -EIO;
> +
> +		if ((ret & MAX9286_VIDEO_DETECT_MASK) == priv->source_mask)
> +			break;
> +
> +		usleep_range(350, 500);
> +	}
> +
> +	if (i == 10) {
> +		dev_err(&priv->client->dev,
> +			"Unable to detect video links: 0x%02x\n", ret);
> +		return -EIO;
> +	}
> +
> +	/* Make sure all enabled links are locked (4ms max). */
> +	for (i = 0; i < 10; i++) {
> +		ret = max9286_read(priv, 0x27);
> +		if (ret < 0)
> +			return -EIO;
> +
> +		if (ret & MAX9286_LOCKED)
> +			break;
> +
> +		usleep_range(350, 450);
> +	}
> +
> +	if (i == 10) {
> +		dev_err(&priv->client->dev, "Not all enabled links locked\n");
> +		return -EIO;
> +	}
> +
> +	return 0;
> +}
> +
> +/*
> + * max9286_check_config_link() - Detect and wait for configuration links
> + *
> + * Determine if the configuration channel is up and settled for a link.
> + *
> + * Returns 0 for success, -EIO for errors.
> + */
> +static int max9286_check_config_link(struct max9286_priv *priv,
> +				     unsigned int source_mask)
> +{
> +	unsigned int conflink_mask = (source_mask & 0x0f) << 4;
> +	unsigned int i;
> +	int ret;
> +
> +	/*
> +	 * Make sure requested configuration links are detected.
> +	 * The delay is not characterized in the chip manual: wait up
> +	 * to 5 milliseconds.
> +	 */
> +	for (i = 0; i < 10; i++) {
> +		ret = max9286_read(priv, 0x49) & 0xf0;
> +		if (ret < 0)
> +			return -EIO;
> +
> +		if (ret == conflink_mask)
> +			break;
> +
> +		usleep_range(350, 500);
> +	}
> +
> +	if (ret != conflink_mask) {
> +		dev_err(&priv->client->dev,
> +			"Unable to detect configuration links: 0x%02x expected 0x%02x\n",
> +			ret, conflink_mask);
> +		return -EIO;
> +	}
> +
> +	dev_info(&priv->client->dev,
> +		 "Successfully detected configuration links after %u loops: 0x%02x\n",
> +		 i, conflink_mask);
> +
> +	return 0;
> +}
> +
> +/* -----------------------------------------------------------------------------
> + * V4L2 Subdev
> + */
> +
> +static int max9286_set_pixelrate(struct max9286_priv *priv)
> +{
> +	struct max9286_source *source = NULL;
> +	u64 pixelrate = 0;
> +
> +	for_each_source(priv, source) {
> +		struct v4l2_ctrl *ctrl;
> +		u64 source_rate = 0;
> +
> +		/* Pixel rate is mandatory to be reported by sources. */
> +		ctrl = v4l2_ctrl_find(source->sd->ctrl_handler,
> +				      V4L2_CID_PIXEL_RATE);
> +		if (!ctrl) {
> +			pixelrate = 0;
> +			break;
> +		}
> +
> +		/* All source must report the same pixel rate. */
> +		source_rate = v4l2_ctrl_g_ctrl_int64(ctrl);
> +		if (!pixelrate) {
> +			pixelrate = source_rate;
> +		} else if (pixelrate != source_rate) {
> +			dev_err(&priv->client->dev,
> +				"Unable to calculate pixel rate\n");
> +			return -EINVAL;
> +		}
> +	}
> +
> +	if (!pixelrate) {
> +		dev_err(&priv->client->dev,
> +			"No pixel rate control available in sources\n");
> +		return -EINVAL;
> +	}
> +
> +	/*
> +	 * The CSI-2 transmitter pixel rate is the single source rate multiplied
> +	 * by the number of available sources.
> +	 */
> +	return v4l2_ctrl_s_ctrl_int64(priv->pixelrate,
> +				      pixelrate * priv->nsources);
> +}
> +
> +static int max9286_notify_bound(struct v4l2_async_notifier *notifier,
> +				struct v4l2_subdev *subdev,
> +				struct v4l2_async_subdev *asd)
> +{
> +	struct max9286_priv *priv = sd_to_max9286(notifier->sd);
> +	struct max9286_source *source = asd_to_max9286_source(asd);
> +	unsigned int index = to_index(priv, source);
> +	unsigned int src_pad;
> +	int ret;
> +
> +	ret = media_entity_get_fwnode_pad(&subdev->entity,
> +					  source->fwnode,
> +					  MEDIA_PAD_FL_SOURCE);
> +	if (ret < 0) {
> +		dev_err(&priv->client->dev,
> +			"Failed to find pad for %s\n", subdev->name);
> +		return ret;
> +	}
> +
> +	priv->bound_sources |= BIT(index);
> +	source->sd = subdev;
> +	src_pad = ret;
> +
> +	ret = media_create_pad_link(&source->sd->entity, src_pad,
> +				    &priv->sd.entity, index,
> +				    MEDIA_LNK_FL_ENABLED |
> +				    MEDIA_LNK_FL_IMMUTABLE);
> +	if (ret) {
> +		dev_err(&priv->client->dev,
> +			"Unable to link %s:%u -> %s:%u\n",
> +			source->sd->name, src_pad, priv->sd.name, index);
> +		return ret;
> +	}
> +
> +	dev_dbg(&priv->client->dev, "Bound %s pad: %u on index %u\n",
> +		subdev->name, src_pad, index);
> +
> +	/*
> +	 * We can only register v4l2_async_notifiers, which do not provide a
> +	 * means to register a complete callback. bound_sources allows us to
> +	 * identify when all remote serializers have completed their probe.
> +	 */
> +	if (priv->bound_sources != priv->source_mask)
> +		return 0;
> +
> +	/*
> +	 * All enabled sources have probed and enabled their reverse control
> +	 * channels:
> +	 *
> +	 * - Verify all configuration links are properly detected
> +	 * - Disable auto-ack as communication on the control channel are now
> +	 *   stable.
> +	 */
> +	max9286_check_config_link(priv, priv->source_mask);
> +
> +	/*
> +	 * Re-configure I2C with local acknowledge disabled after cameras have
> +	 * probed.
> +	 */
> +	max9286_configure_i2c(priv, false);
> +
> +	return max9286_set_pixelrate(priv);
> +}
> +
> +static void max9286_notify_unbind(struct v4l2_async_notifier *notifier,
> +				  struct v4l2_subdev *subdev,
> +				  struct v4l2_async_subdev *asd)
> +{
> +	struct max9286_priv *priv = sd_to_max9286(notifier->sd);
> +	struct max9286_source *source = asd_to_max9286_source(asd);
> +	unsigned int index = to_index(priv, source);
> +
> +	source->sd = NULL;
> +	priv->bound_sources &= ~BIT(index);
> +}
> +
> +static const struct v4l2_async_notifier_operations max9286_notify_ops = {
> +	.bound = max9286_notify_bound,
> +	.unbind = max9286_notify_unbind,
> +};
> +
> +static int max9286_v4l2_notifier_register(struct max9286_priv *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	struct max9286_source *source = NULL;
> +	int ret;
> +
> +	if (!priv->nsources)
> +		return 0;
> +
> +	v4l2_async_notifier_init(&priv->notifier);
> +
> +	for_each_source(priv, source) {
> +		unsigned int i = to_index(priv, source);
> +
> +		source->asd.match_type = V4L2_ASYNC_MATCH_FWNODE;
> +		source->asd.match.fwnode = source->fwnode;
> +
> +		ret = v4l2_async_notifier_add_subdev(&priv->notifier,
> +						     &source->asd);
> +		if (ret) {
> +			dev_err(dev, "Failed to add subdev for source %d", i);
> +			v4l2_async_notifier_cleanup(&priv->notifier);
> +			return ret;
> +		}
> +
> +		/*
> +		 * Balance the reference counting handled through
> +		 * v4l2_async_notifier_cleanup()
> +		 */
> +		fwnode_handle_get(source->fwnode);
> +	}
> +
> +	priv->notifier.ops = &max9286_notify_ops;
> +
> +	ret = v4l2_async_subdev_notifier_register(&priv->sd, &priv->notifier);
> +	if (ret) {
> +		dev_err(dev, "Failed to register subdev_notifier");
> +		v4l2_async_notifier_cleanup(&priv->notifier);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void max9286_v4l2_notifier_unregister(struct max9286_priv *priv)
> +{
> +	if (!priv->nsources)
> +		return;
> +
> +	v4l2_async_notifier_unregister(&priv->notifier);
> +	v4l2_async_notifier_cleanup(&priv->notifier);
> +}
> +
> +static int max9286_s_stream(struct v4l2_subdev *sd, int enable)
> +{
> +	struct max9286_priv *priv = sd_to_max9286(sd);
> +	struct max9286_source *source;
> +	unsigned int i;
> +	bool sync = false;
> +	int ret;
> +
> +	if (enable) {
> +		/*
> +		 * The frame sync between cameras is transmitted across the
> +		 * reverse channel as GPIO. We must open all channels while
> +		 * streaming to allow this synchronisation signal to be shared.
> +		 */
> +		max9286_i2c_mux_open(priv);
> +
> +		/* Start all cameras. */
> +		for_each_source(priv, source) {
> +			ret = v4l2_subdev_call(source->sd, video, s_stream, 1);
> +			if (ret)
> +				return ret;
> +		}
> +
> +		ret = max9286_check_video_links(priv);
> +		if (ret)
> +			return ret;
> +
> +		/*
> +		 * Wait until frame synchronization is locked.
> +		 *
> +		 * Manual says frame sync locking should take ~6 VTS.
> +		 * From practical experience at least 8 are required. Give
> +		 * 12 complete frames time (~400ms at 30 fps) to achieve frame
> +		 * locking before returning error.
> +		 */
> +		for (i = 0; i < 40; i++) {
> +			if (max9286_read(priv, 0x31) & MAX9286_FSYNC_LOCKED) {
> +				sync = true;
> +				break;
> +			}
> +			usleep_range(9000, 11000);
> +		}
> +
> +		if (!sync) {
> +			dev_err(&priv->client->dev,
> +				"Failed to get frame synchronization\n");
> +			return -EXDEV; /* Invalid cross-device link */
> +		}
> +
> +		/*
> +		 * Enable CSI output, VC set according to link number.
> +		 * Bit 7 must be set (chip manual says it's 0 and reserved).
> +		 */
> +		max9286_write(priv, 0x15, 0x80 | MAX9286_VCTYPE |
> +			      MAX9286_CSIOUTEN | MAX9286_0X15_RESV);
> +	} else {
> +		max9286_write(priv, 0x15, MAX9286_VCTYPE | MAX9286_0X15_RESV);
> +
> +		/* Stop all cameras. */
> +		for_each_source(priv, source)
> +			v4l2_subdev_call(source->sd, video, s_stream, 0);
> +
> +		max9286_i2c_mux_close(priv);
> +	}
> +
> +	return 0;
> +}
> +
> +static int max9286_enum_mbus_code(struct v4l2_subdev *sd,
> +				  struct v4l2_subdev_pad_config *cfg,
> +				  struct v4l2_subdev_mbus_code_enum *code)
> +{
> +	if (code->pad || code->index > 0)
> +		return -EINVAL;
> +
> +	code->code = MEDIA_BUS_FMT_UYVY8_1X16;
> +
> +	return 0;
> +}
> +
> +static struct v4l2_mbus_framefmt *
> +max9286_get_pad_format(struct max9286_priv *priv,
> +		       struct v4l2_subdev_pad_config *cfg,
> +		       unsigned int pad, u32 which)
> +{
> +	switch (which) {
> +	case V4L2_SUBDEV_FORMAT_TRY:
> +		return v4l2_subdev_get_try_format(&priv->sd, cfg, pad);
> +	case V4L2_SUBDEV_FORMAT_ACTIVE:
> +		return &priv->fmt[pad];
> +	default:
> +		return NULL;
> +	}
> +}
> +
> +static int max9286_set_fmt(struct v4l2_subdev *sd,
> +			   struct v4l2_subdev_pad_config *cfg,
> +			   struct v4l2_subdev_format *format)
> +{
> +	struct max9286_priv *priv = sd_to_max9286(sd);
> +	struct v4l2_mbus_framefmt *cfg_fmt;
> +
> +	if (format->pad == MAX9286_SRC_PAD)
> +		return -EINVAL;
> +
> +	/* Refuse non YUV422 formats as we hardcode DT to 8 bit YUV422 */
> +	switch (format->format.code) {
> +	case MEDIA_BUS_FMT_UYVY8_1X16:
> +	case MEDIA_BUS_FMT_VYUY8_1X16:
> +	case MEDIA_BUS_FMT_YUYV8_1X16:
> +	case MEDIA_BUS_FMT_YVYU8_1X16:
> +		break;
> +	default:
> +		format->format.code = MEDIA_BUS_FMT_UYVY8_1X16;
> +		break;
> +	}
> +
> +	cfg_fmt = max9286_get_pad_format(priv, cfg, format->pad, format->which);
> +	if (!cfg_fmt)
> +		return -EINVAL;
> +
> +	mutex_lock(&priv->mutex);
> +	*cfg_fmt = format->format;
> +	mutex_unlock(&priv->mutex);
> +
> +	return 0;
> +}
> +
> +static int max9286_get_fmt(struct v4l2_subdev *sd,
> +			   struct v4l2_subdev_pad_config *cfg,
> +			   struct v4l2_subdev_format *format)
> +{
> +	struct max9286_priv *priv = sd_to_max9286(sd);
> +	struct v4l2_mbus_framefmt *cfg_fmt;
> +	unsigned int pad = format->pad;
> +
> +	/*
> +	 * Multiplexed Stream Support: Support link validation by returning the
> +	 * format of the first bound link. All links must have the same format,
> +	 * as we do not support mixing and matching of cameras connected to the
> +	 * max9286.
> +	 */
> +	if (pad == MAX9286_SRC_PAD)
> +		pad = __ffs(priv->bound_sources);
> +
> +	cfg_fmt = max9286_get_pad_format(priv, cfg, pad, format->which);
> +	if (!cfg_fmt)
> +		return -EINVAL;
> +
> +	mutex_lock(&priv->mutex);
> +	format->format = *cfg_fmt;
> +	mutex_unlock(&priv->mutex);
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_subdev_video_ops max9286_video_ops = {
> +	.s_stream	= max9286_s_stream,
> +};
> +
> +static const struct v4l2_subdev_pad_ops max9286_pad_ops = {
> +	.enum_mbus_code = max9286_enum_mbus_code,
> +	.get_fmt	= max9286_get_fmt,
> +	.set_fmt	= max9286_set_fmt,
> +};
> +
> +static const struct v4l2_subdev_ops max9286_subdev_ops = {
> +	.video		= &max9286_video_ops,
> +	.pad		= &max9286_pad_ops,
> +};
> +
> +static void max9286_init_format(struct v4l2_mbus_framefmt *fmt)
> +{
> +	fmt->width		= 1280;
> +	fmt->height		= 800;
> +	fmt->code		= MEDIA_BUS_FMT_UYVY8_1X16;
> +	fmt->colorspace		= V4L2_COLORSPACE_SRGB;
> +	fmt->field		= V4L2_FIELD_NONE;
> +	fmt->ycbcr_enc		= V4L2_YCBCR_ENC_DEFAULT;
> +	fmt->quantization	= V4L2_QUANTIZATION_DEFAULT;
> +	fmt->xfer_func		= V4L2_XFER_FUNC_DEFAULT;
> +}
> +
> +static int max9286_open(struct v4l2_subdev *subdev, struct v4l2_subdev_fh *fh)
> +{
> +	struct v4l2_mbus_framefmt *format;
> +	unsigned int i;
> +
> +	for (i = 0; i < MAX9286_N_SINKS; i++) {
> +		format = v4l2_subdev_get_try_format(subdev, fh->pad, i);
> +		max9286_init_format(format);
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_subdev_internal_ops max9286_subdev_internal_ops = {
> +	.open = max9286_open,
> +};
> +
> +static int max9286_s_ctrl(struct v4l2_ctrl *ctrl)
> +{
> +	switch (ctrl->id) {
> +	case V4L2_CID_PIXEL_RATE:
> +		return 0;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct v4l2_ctrl_ops max9286_ctrl_ops = {
> +	.s_ctrl = max9286_s_ctrl,
> +};
> +
> +static int max9286_v4l2_register(struct max9286_priv *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	struct fwnode_handle *ep;
> +	int ret;
> +	int i;
> +
> +	/* Register v4l2 async notifiers for connected Camera subdevices */
> +	ret = max9286_v4l2_notifier_register(priv);
> +	if (ret) {
> +		dev_err(dev, "Unable to register V4L2 async notifiers\n");
> +		return ret;
> +	}
> +
> +	/* Configure V4L2 for the MAX9286 itself */
> +
> +	for (i = 0; i < MAX9286_N_SINKS; i++)
> +		max9286_init_format(&priv->fmt[i]);
> +
> +	v4l2_i2c_subdev_init(&priv->sd, priv->client, &max9286_subdev_ops);
> +	priv->sd.internal_ops = &max9286_subdev_internal_ops;
> +	priv->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> +
> +	v4l2_ctrl_handler_init(&priv->ctrls, 1);
> +	priv->pixelrate = v4l2_ctrl_new_std(&priv->ctrls,
> +					    &max9286_ctrl_ops,
> +					    V4L2_CID_PIXEL_RATE,
> +					    1, INT_MAX, 1, 50000000);
> +
> +	priv->sd.ctrl_handler = &priv->ctrls;
> +	ret = priv->ctrls.error;
> +	if (ret)
> +		goto err_async;
> +
> +	priv->sd.entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
> +
> +	priv->pads[MAX9286_SRC_PAD].flags = MEDIA_PAD_FL_SOURCE;
> +	for (i = 0; i < MAX9286_SRC_PAD; i++)
> +		priv->pads[i].flags = MEDIA_PAD_FL_SINK;
> +	ret = media_entity_pads_init(&priv->sd.entity, MAX9286_N_PADS,
> +				     priv->pads);
> +	if (ret)
> +		goto err_async;
> +
> +	ep = fwnode_graph_get_endpoint_by_id(dev_fwnode(dev), MAX9286_SRC_PAD,
> +					     0, 0);
> +	if (!ep) {
> +		dev_err(dev, "Unable to retrieve endpoint on \"port@4\"\n");
> +		ret = -ENOENT;
> +		goto err_async;
> +	}
> +	priv->sd.fwnode = ep;
> +
> +	ret = v4l2_async_register_subdev(&priv->sd);
> +	if (ret < 0) {
> +		dev_err(dev, "Unable to register subdevice\n");
> +		goto err_put_node;
> +	}
> +
> +	return 0;
> +
> +err_put_node:
> +	fwnode_handle_put(ep);
> +err_async:
> +	max9286_v4l2_notifier_unregister(priv);
> +
> +	return ret;
> +}
> +
> +static void max9286_v4l2_unregister(struct max9286_priv *priv)
> +{
> +	fwnode_handle_put(priv->sd.fwnode);
> +	v4l2_async_unregister_subdev(&priv->sd);
> +	max9286_v4l2_notifier_unregister(priv);
> +}
> +
> +/* -----------------------------------------------------------------------------
> + * Probe/Remove
> + */
> +
> +static int max9286_setup(struct max9286_priv *priv)
> +{
> +	/*
> +	 * Link ordering values for all enabled links combinations. Orders must
> +	 * be assigned sequentially from 0 to the number of enabled links
> +	 * without leaving any hole for disabled links. We thus assign orders to
> +	 * enabled links first, and use the remaining order values for disabled
> +	 * links are all links must have a different order value;
> +	 */
> +	static const u8 link_order[] = {
> +		(3 << 6) | (2 << 4) | (1 << 2) | (0 << 0), /* xxxx */
> +		(3 << 6) | (2 << 4) | (1 << 2) | (0 << 0), /* xxx0 */
> +		(3 << 6) | (2 << 4) | (0 << 2) | (1 << 0), /* xx0x */
> +		(3 << 6) | (2 << 4) | (1 << 2) | (0 << 0), /* xx10 */
> +		(3 << 6) | (0 << 4) | (2 << 2) | (1 << 0), /* x0xx */
> +		(3 << 6) | (1 << 4) | (2 << 2) | (0 << 0), /* x1x0 */
> +		(3 << 6) | (1 << 4) | (0 << 2) | (2 << 0), /* x10x */
> +		(3 << 6) | (1 << 4) | (1 << 2) | (0 << 0), /* x210 */
> +		(0 << 6) | (3 << 4) | (2 << 2) | (1 << 0), /* 0xxx */
> +		(1 << 6) | (3 << 4) | (2 << 2) | (0 << 0), /* 1xx0 */
> +		(1 << 6) | (3 << 4) | (0 << 2) | (2 << 0), /* 1x0x */
> +		(2 << 6) | (3 << 4) | (1 << 2) | (0 << 0), /* 2x10 */
> +		(1 << 6) | (0 << 4) | (3 << 2) | (2 << 0), /* 10xx */
> +		(2 << 6) | (1 << 4) | (3 << 2) | (0 << 0), /* 21x0 */
> +		(2 << 6) | (1 << 4) | (0 << 2) | (3 << 0), /* 210x */
> +		(3 << 6) | (2 << 4) | (1 << 2) | (0 << 0), /* 3210 */
> +	};
> +
> +	/*
> +	 * Set the I2C bus speed.
> +	 *
> +	 * Enable I2C Local Acknowledge during the probe sequences of the camera
> +	 * only. This should be disabled after the mux is initialised.
> +	 */
> +	max9286_configure_i2c(priv, true);
> +
> +	/*
> +	 * Reverse channel setup.
> +	 *
> +	 * - Enable custom reverse channel configuration (through register 0x3f)
> +	 *   and set the first pulse length to 35 clock cycles.
> +	 * - Increase the reverse channel amplitude to 170mV to accommodate the
> +	 *   high threshold enabled by the serializer driver.
> +	 */
> +	max9286_write(priv, 0x3f, MAX9286_EN_REV_CFG | MAX9286_REV_FLEN(35));
> +	max9286_write(priv, 0x3b, MAX9286_REV_TRF(1) | MAX9286_REV_AMP(70) |
> +		      MAX9286_REV_AMP_X);
> +	usleep_range(2000, 2500);
> +
> +	/*
> +	 * Enable GMSL links, mask unused ones and autodetect link
> +	 * used as CSI clock source.
> +	 */
> +	max9286_write(priv, 0x00, MAX9286_MSTLINKSEL_AUTO | priv->route_mask);
> +	max9286_write(priv, 0x0b, link_order[priv->route_mask]);
> +	max9286_write(priv, 0x69, (0xf & ~priv->route_mask));
> +
> +	/*
> +	 * Video format setup:
> +	 * Disable CSI output, VC is set according to Link number.
> +	 */
> +	max9286_write(priv, 0x15, MAX9286_VCTYPE | MAX9286_0X15_RESV);
> +
> +	/* Enable CSI-2 Lane D0-D3 only, DBL mode, YUV422 8-bit. */
> +	max9286_write(priv, 0x12, MAX9286_CSIDBL | MAX9286_DBL |
> +		      MAX9286_CSILANECNT(priv->csi2_data_lanes) |
> +		      MAX9286_DATATYPE_YUV422_8BIT);
> +
> +	/* Automatic: FRAMESYNC taken from the slowest Link. */
> +	max9286_write(priv, 0x01, MAX9286_FSYNCMODE_INT_HIZ |
> +		      MAX9286_FSYNCMETH_AUTO);
> +
> +	/* Enable HS/VS encoding, use D14/15 for HS/VS, invert VS. */
> +	max9286_write(priv, 0x0c, MAX9286_HVEN | MAX9286_INVVS |
> +		      MAX9286_HVSRC_D14);
> +
> +	/*
> +	 * The overlap window seems to provide additional validation by tracking
> +	 * the delay between vsync and frame sync, generating an error if the
> +	 * delay is bigger than the programmed window, though it's not yet clear
> +	 * what value should be set.
> +	 *
> +	 * As it's an optional value and can be disabled, we do so by setting
> +	 * a 0 overlap value.
> +	 */
> +	max9286_write(priv, 0x63, 0);
> +	max9286_write(priv, 0x64, 0);
> +
> +	/*
> +	 * Wait for 2ms to allow the link to resynchronize after the
> +	 * configuration change.
> +	 */
> +	usleep_range(2000, 5000);
> +
> +	return 0;
> +}
> +
> +static void max9286_gpio_set(struct gpio_chip *chip,
> +			     unsigned int offset, int value)
> +{
> +	struct max9286_priv *priv = gpiochip_get_data(chip);
> +
> +	if (value)
> +		priv->gpio_state |= BIT(offset);
> +	else
> +		priv->gpio_state &= ~BIT(offset);
> +
> +	max9286_write(priv, 0x0f, MAX9286_0X0F_RESERVED | priv->gpio_state);
> +}
> +
> +static int max9286_gpio_get(struct gpio_chip *chip, unsigned int offset)
> +{
> +	struct max9286_priv *priv = gpiochip_get_data(chip);
> +
> +	return priv->gpio_state & BIT(offset);
> +}
> +
> +static int max9286_register_gpio(struct max9286_priv *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	struct gpio_chip *gpio = &priv->gpio;
> +	int ret;
> +
> +	/* Configure the GPIO */
> +	gpio->label = dev_name(dev);
> +	gpio->parent = dev;
> +	gpio->owner = THIS_MODULE;
> +	gpio->of_node = dev->of_node;
> +	gpio->ngpio = 2;
> +	gpio->base = -1;
> +	gpio->set = max9286_gpio_set;
> +	gpio->get = max9286_gpio_get;
> +	gpio->can_sleep = true;
> +
> +	/* GPIO values default to high */
> +	priv->gpio_state = BIT(0) | BIT(1);
> +
> +	ret = devm_gpiochip_add_data(dev, gpio, priv);
> +	if (ret)
> +		dev_err(dev, "Unable to create gpio_chip\n");
> +
> +	return ret;
> +}
> +
> +static int max9286_init(struct device *dev)
> +{
> +	struct max9286_priv *priv;
> +	struct i2c_client *client;
> +	int ret;
> +
> +	client = to_i2c_client(dev);
> +	priv = i2c_get_clientdata(client);
> +
> +	/* Enable the bus power. */
> +	ret = regulator_enable(priv->regulator);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "Unable to turn PoC on\n");
> +		return ret;
> +	}
> +
> +	ret = max9286_setup(priv);
> +	if (ret) {
> +		dev_err(dev, "Unable to setup max9286\n");
> +		goto err_regulator;
> +	}
> +
> +	/*
> +	 * Register all V4L2 interactions for the MAX9286 and notifiers for
> +	 * any subdevices connected.
> +	 */
> +	ret = max9286_v4l2_register(priv);
> +	if (ret) {
> +		dev_err(dev, "Failed to register with V4L2\n");
> +		goto err_regulator;
> +	}
> +
> +	ret = max9286_i2c_mux_init(priv);
> +	if (ret) {
> +		dev_err(dev, "Unable to initialize I2C multiplexer\n");
> +		goto err_v4l2_register;
> +	}
> +
> +	/* Leave the mux channels disabled until they are selected. */
> +	max9286_i2c_mux_close(priv);
> +
> +	return 0;
> +
> +err_v4l2_register:
> +	max9286_v4l2_unregister(priv);
> +err_regulator:
> +	regulator_disable(priv->regulator);
> +
> +	return ret;
> +}
> +
> +static void max9286_cleanup_dt(struct max9286_priv *priv)
> +{
> +	struct max9286_source *source;
> +
> +	for_each_source(priv, source) {
> +		fwnode_handle_put(source->fwnode);
> +		source->fwnode = NULL;
> +	}
> +}
> +
> +static int max9286_parse_dt(struct max9286_priv *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	struct device_node *i2c_mux;
> +	struct device_node *node = NULL;
> +	unsigned int i2c_mux_mask = 0;
> +
> +	/* Balance the of_node_put() performed by of_find_node_by_name(). */
> +	of_node_get(dev->of_node);
> +	i2c_mux = of_find_node_by_name(dev->of_node, "i2c-mux");
> +	if (!i2c_mux) {
> +		dev_err(dev, "Failed to find i2c-mux node\n");
> +		return -EINVAL;
> +	}
> +
> +	/* Identify which i2c-mux channels are enabled */
> +	for_each_child_of_node(i2c_mux, node) {
> +		u32 id = 0;
> +
> +		of_property_read_u32(node, "reg", &id);
> +		if (id >= MAX9286_NUM_GMSL)
> +			continue;
> +
> +		if (!of_device_is_available(node)) {
> +			dev_dbg(dev, "Skipping disabled I2C bus port %u\n", id);
> +			continue;
> +		}
> +
> +		i2c_mux_mask |= BIT(id);
> +	}
> +	of_node_put(node);
> +	of_node_put(i2c_mux);
> +
> +	/* Parse the endpoints */
> +	for_each_endpoint_of_node(dev->of_node, node) {
> +		struct max9286_source *source;
> +		struct of_endpoint ep;
> +
> +		of_graph_parse_endpoint(node, &ep);
> +		dev_dbg(dev, "Endpoint %pOF on port %d",
> +			ep.local_node, ep.port);
> +
> +		if (ep.port > MAX9286_NUM_GMSL) {
> +			dev_err(dev, "Invalid endpoint %s on port %d",
> +				of_node_full_name(ep.local_node), ep.port);
> +			continue;
> +		}
> +
> +		/* For the source endpoint just parse the bus configuration. */
> +		if (ep.port == MAX9286_SRC_PAD) {
> +			struct v4l2_fwnode_endpoint vep = {
> +				.bus_type = V4L2_MBUS_CSI2_DPHY
> +			};
> +			int ret;
> +
> +			ret = v4l2_fwnode_endpoint_parse(
> +					of_fwnode_handle(node), &vep);
> +			if (ret) {
> +				of_node_put(node);
> +				return ret;
> +			}
> +
> +			priv->csi2_data_lanes =
> +				vep.bus.mipi_csi2.num_data_lanes;
> +
> +			continue;
> +		}
> +
> +		/* Skip if the corresponding GMSL link is unavailable. */
> +		if (!(i2c_mux_mask & BIT(ep.port)))
> +			continue;
> +
> +		if (priv->sources[ep.port].fwnode) {
> +			dev_err(dev,
> +				"Multiple port endpoints are not supported: %d",
> +				ep.port);
> +
> +			continue;
> +		}
> +
> +		source = &priv->sources[ep.port];
> +		source->fwnode = fwnode_graph_get_remote_endpoint(
> +						of_fwnode_handle(node));
> +		if (!source->fwnode) {
> +			dev_err(dev,
> +				"Endpoint %pOF has no remote endpoint connection\n",
> +				ep.local_node);
> +
> +			continue;
> +		}
> +
> +		priv->source_mask |= BIT(ep.port);
> +		priv->nsources++;
> +	}
> +	of_node_put(node);
> +
> +	priv->route_mask = priv->source_mask;
> +
> +	return 0;
> +}
> +
> +static int max9286_probe(struct i2c_client *client)
> +{
> +	struct max9286_priv *priv;
> +	int ret;
> +
> +	priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	mutex_init(&priv->mutex);
> +
> +	priv->client = client;
> +	i2c_set_clientdata(client, priv);
> +
> +	priv->gpiod_pwdn = devm_gpiod_get_optional(&client->dev, "enable",
> +						   GPIOD_OUT_HIGH);
> +	if (IS_ERR(priv->gpiod_pwdn))
> +		return PTR_ERR(priv->gpiod_pwdn);
> +
> +	gpiod_set_consumer_name(priv->gpiod_pwdn, "max9286-pwdn");
> +	gpiod_set_value_cansleep(priv->gpiod_pwdn, 1);
> +
> +	/* Wait at least 4ms before the I2C lines latch to the address */
> +	if (priv->gpiod_pwdn)
> +		usleep_range(4000, 5000);
> +
> +	/*
> +	 * The MAX9286 starts by default with all ports enabled, we disable all
> +	 * ports early to ensure that all channels are disabled if we error out
> +	 * and keep the bus consistent.
> +	 */
> +	max9286_i2c_mux_close(priv);
> +
> +	/*
> +	 * The MAX9286 initialises with auto-acknowledge enabled by default.
> +	 * This can be invasive to other transactions on the same bus, so
> +	 * disable it early. It will be enabled only as and when needed.
> +	 */
> +	max9286_configure_i2c(priv, false);
> +
> +	ret = max9286_register_gpio(priv);
> +	if (ret)
> +		goto err_powerdown;
> +
> +	priv->regulator = devm_regulator_get(&client->dev, "poc");
> +	if (IS_ERR(priv->regulator)) {
> +		if (PTR_ERR(priv->regulator) != -EPROBE_DEFER)
> +			dev_err(&client->dev,
> +				"Unable to get PoC regulator (%ld)\n",
> +				PTR_ERR(priv->regulator));
> +		ret = PTR_ERR(priv->regulator);
> +		goto err_powerdown;
> +	}
> +
> +	ret = max9286_parse_dt(priv);
> +	if (ret)
> +		goto err_powerdown;
> +
> +	ret = max9286_init(&client->dev);
> +	if (ret < 0)
> +		goto err_cleanup_dt;
> +
> +	return 0;
> +
> +err_cleanup_dt:
> +	max9286_cleanup_dt(priv);
> +err_powerdown:
> +	gpiod_set_value_cansleep(priv->gpiod_pwdn, 0);
> +
> +	return ret;
> +}
> +
> +static int max9286_remove(struct i2c_client *client)
> +{
> +	struct max9286_priv *priv = i2c_get_clientdata(client);
> +
> +	i2c_mux_del_adapters(priv->mux);
> +
> +	max9286_v4l2_unregister(priv);
> +
> +	regulator_disable(priv->regulator);
> +
> +	gpiod_set_value_cansleep(priv->gpiod_pwdn, 0);
> +
> +	max9286_cleanup_dt(priv);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id max9286_dt_ids[] = {
> +	{ .compatible = "maxim,max9286" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, max9286_dt_ids);
> +
> +static struct i2c_driver max9286_i2c_driver = {
> +	.driver	= {
> +		.name		= "max9286",
> +		.of_match_table	= of_match_ptr(max9286_dt_ids),
> +	},
> +	.probe_new	= max9286_probe,
> +	.remove		= max9286_remove,
> +};
> +
> +module_i2c_driver(max9286_i2c_driver);
> +
> +MODULE_DESCRIPTION("Maxim MAX9286 GMSL Deserializer Driver");
> +MODULE_AUTHOR("Jacopo Mondi, Kieran Bingham, Laurent Pinchart, Niklas Söderlund, Vladimir Barinov");
> +MODULE_LICENSE("GPL");
> -- 
> 2.25.1
>
Kieran Bingham July 16, 2020, 9:02 a.m. UTC | #2
Hi Sakari,

This is the output of checkpatch --strict on this driver. Sorry for not
detailing this in the commit or cover letter.

> ./patches/gmsl/v10/v10-0001-dt-bindings-media-i2c-Add-bindings-for-Maxim-Int.patch has style problems, please review.
> --------------------------------------------------------------
> ./patches/gmsl/v10/v10-0002-media-i2c-Add-MAX9286-driver.patch
> --------------------------------------------------------------
> CHECK: Prefer using the BIT macro
> #246: FILE: drivers/media/i2c/max9286.c:40:
> +#define MAX9286_FSYNCMODE_INT_OUT	(1 << 6)
> 
> CHECK: Prefer using the BIT macro
> #251: FILE: drivers/media/i2c/max9286.c:45:
> +#define MAX9286_FSYNCMETH_SEMI_AUTO	(1 << 0)
> 
> CHECK: Prefer using the BIT macro
> #262: FILE: drivers/media/i2c/max9286.c:56:
> +#define MAX9286_EDC_6BIT_CRC		(1 << 5)
> 
> CHECK: Prefer using the BIT macro
> #268: FILE: drivers/media/i2c/max9286.c:62:
> +#define MAX9286_HVSRC_D14		(1 << 0)
> 
> CHECK: Prefer using the BIT macro
> #286: FILE: drivers/media/i2c/max9286.c:80:
> +#define MAX9286_DATATYPE_RGB565		(1 << 0)
> 
> CHECK: Prefer using the BIT macro
> #304: FILE: drivers/media/i2c/max9286.c:98:
> +#define MAX9286_I2CSLVSH_469NS_234NS	(1 << 5)
> 
> CHECK: Prefer using the BIT macro
> #312: FILE: drivers/media/i2c/max9286.c:106:
> +#define MAX9286_I2CMSTBT_28KBPS		(1 << 2)
> 
> CHECK: Prefer using the BIT macro
> #316: FILE: drivers/media/i2c/max9286.c:110:
> +#define MAX9286_I2CSLVTO_256US		(1 << 0)

None of those are appropriate to use the BIT() macro, as they are all
entries of a specific field with a shift, such as:

#define MAX9286_FSYNCMODE_ECU           (3 << 6)
#define MAX9286_FSYNCMODE_EXT           (2 << 6)
#define MAX9286_FSYNCMODE_INT_OUT       (1 << 6)
#define MAX9286_FSYNCMODE_INT_HIZ       (0 << 6)

Checkpatch is only picking up on the "1 << x" variant of each entry.


> CHECK: Macro argument reuse 'source' - possible side-effects?
> #399: FILE: drivers/media/i2c/max9286.c:193:
> +#define for_each_source(priv, source) \
> +	for ((source) = NULL; ((source) = next_source((priv), (source))); )

This warns against possible side effects, but the 're-use' effects are
desired ;-)

If you'd prefer this macro to be re-written please let me know.


> CHECK: Lines should not end with a '('
> #1372: FILE: drivers/media/i2c/max9286.c:1166:
> +			ret = v4l2_fwnode_endpoint_parse(

Full code block:

>                         ret = v4l2_fwnode_endpoint_parse(
>                                         of_fwnode_handle(node), &vep);
>                         if (ret) {
>                                 of_node_put(node);
>                                 return ret;
>                         }

That one is awkward, and I chose to keep it as a lesser evil.
Of course now that we can officially go up to 120 chars, I could move
this line up.

If you'd like this to be moved to a single line now we can go over 80
chars, please confirm.

> 
> CHECK: Lines should not end with a '('
> #1398: FILE: drivers/media/i2c/max9286.c:1192:
> +		source->fwnode = fwnode_graph_get_remote_endpoint(

Same here, it was unavoidable to go over 80 chars, so this was the break
point.

If you would now like to join these lines, I can do so.


> 
> total: 0 errors, 0 warnings, 11 checks, 1362 lines checked


--
Kieran



On 12/06/2020 15:47, Kieran Bingham wrote:
> The MAX9286 is a 4-channel GMSL deserializer with coax or STP input and
> CSI-2 output. The device supports multicamera streaming applications,
> and features the ability to synchronise the attached cameras.
> 
> CSI-2 output can be configured with 1 to 4 lanes, and a control channel
> is supported over I2C, which implements an I2C mux to facilitate
> communications with connected cameras across the reverse control
> channel.
> 
> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> 
> --
> v2:
>  - Fix MAINTAINERS entry
> 
> This posting is released with the following modifications to work
> without Sakari's VC developments:
>  - max9286_g_mbus_config() re-instated
>  - max9286_get_frame_desc() is not bus/csi aware
>  - max9286_{get,set}_routing() removed
> 
> v3:
>  - Initialise notifier with v4l2_async_notifier_init
>  - Update for new mbus csi2 format V4L2_MBUS_CSI2_DPHY
> 
> v4: - Re-introduce required code to function with the VC series.
> 
>  - Implement max9286_get_routing, max9286_set_routing
>  - Remove max9286_g_mbus_config
> 
> v5: (internal release)
>  - Fix printk formatting for hex value
>  - max9286->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE (add |)
>  - MEDIA_ENT_F_PROC_VIDEO_PIXEL_FORMATTER -> MEDIA_ENT_F_VID_IF_BRIDGE
>  - Remove 'device is bound' workaround
> 
> v6:
>  - v4l2_subdev_krouting instead of v4l2_subdev_routing separated
>    to allow integration without the VC/V4L2-Mux series.
>  - convert sd_to_max9286 to inline function
>  - rename max9286_device to max9286_priv
>  - Cleanup the v4l2_async_notifier
>  - Extend MODULE_AUTHOR
>  - Replace of_graph_get_endpoint_by_regs with fwnode_graph_get_endpoint_by_id
>  - Pass default bus type when parsing fwnode endpoint (Manivannan Sadhasivam)
>  - Use new YAML file reference in MAINTAINERS
>  - Parse new i2c-mux node in max9286_get_i2c_by_id
>    (This could/should be refactored to parse these separately first)
>  - Spelling and calculation fixes in the FSYNC_LOCKED check comments
>  - Identify each enabled i2c-mux channel in a single pass
>  - max9286: Improve mux-state readbility [v2]
>  - Fix frame sync lock durations
>  - Add comment to describe /why/ we must open the mux in s_stream
>  - use -EXDEV as return code for failed link synchronisation.
>  - Fix reference counting of the dt nodeS
>  - Convert to probe_new for I2C
>  - Remove redundant max9286_i2c_mux_state
>  - Provide optional enable-gpio (max9286-pwdn)
> 
> v7:
>  [Kieran]
>  - Ensure powerdown lines are optional
>  - Add a 4ms power-up delay
>  - Add max9286_check_config_link() to core
>  - Add GPIO chip controller for GPIO0OUT and GPIO1OUT
>  - Fix GPIO registration
>  - max9286: Split out async registration
>    (fixes regulator -EPROBE_DEFERs failures)
>  - Collect all V4L2 registrations
>  - balance v4l2_async refcnting
>  - Rename max9286_v4l2_async_ => max9286_v4l2_notifier_
> 
>  [Jacopo]
>  - Remove redundanct MAXIM_I2C_SPEED macros
>  - Move notifiers operations
>  - Add delay after reverse channel reconfiguration
>  - Move link setup to completion
>  - Fix up max9286_check_config_link() implementation
>  - Remove redundant dual configuration of reverse channel
> 
> v8:
> 
> [Kieran]
>  - Update the bound_sources mask on unbind
>  - Convert probe kzalloc usage to devm_ variant
>  - Fix up cleanup path from GPIO PowerDown registration
>  - cleanup GPIO device registration fail path
>  - Convert to use devm_regulator_get()
>  - Fit max9286_parse_dt print on one line
>  - Move multi-device workarounds out of upstream driver
>  - Remove I2C mod-table
>  - Lock format changes
>  - Describe pad index usage
>  - Remove poc_enabled workaround
>  - Rename the max9286_gpio to be more explicit on it's actions.
>  - Move max9286_init_format call
>  - Rework probe sequence and simplify error paths.
>  - Simplify i2c comments
>  - Implement Pixelrate control
>  - Disable overlap window
> 
> [Jacopo]
>  - Adapt Kconfig to latest upstream changes
>  - Put of node on error
>  - Calculate pixel rate
>  - Simplify overlap window disablement
> 
> v9:
> 
> [Kieran]
>  - Kconfig: Depend on OF
>  - Re-sort addition to Makefile
> 
> v10:
> 
> [Kieran]
>  - Use the same default mbus_fmt everywhere
>  - Don't provide GPIO names
>  - Fix dev->of_node refcnting
>  - Fix whitespace indent
>  - Use single sample per pixel
>  - Remove redundant DPHY check
>  - Remove redundant v4l2_fwnode_endpoint_free call
>  - Validate link formats
> ---
>  MAINTAINERS                 |   10 +
>  drivers/media/i2c/Kconfig   |   13 +
>  drivers/media/i2c/Makefile  |    1 +
>  drivers/media/i2c/max9286.c | 1320 +++++++++++++++++++++++++++++++++++
>  4 files changed, 1344 insertions(+)
>  create mode 100644 drivers/media/i2c/max9286.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 791d2a862e41..7534df72033f 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -10274,6 +10274,16 @@ F:	Documentation/hwmon/max6697.rst
>  F:	drivers/hwmon/max6697.c
>  F:	include/linux/platform_data/max6697.h
>  
> +MAX9286 QUAD GMSL DESERIALIZER DRIVER
> +M:	Jacopo Mondi <jacopo+renesas@jmondi.org>
> +M:	Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> +M:	Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> +M:	Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> +L:	linux-media@vger.kernel.org
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
> +F:	drivers/media/i2c/max9286.c
> +
>  MAX9860 MONO AUDIO VOICE CODEC DRIVER
>  M:	Peter Rosin <peda@axentia.se>
>  L:	alsa-devel@alsa-project.org (moderated for non-subscribers)
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index da11036ad804..0a083407aa3e 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -464,6 +464,19 @@ config VIDEO_VPX3220
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called vpx3220.
>  
> +config VIDEO_MAX9286
> +	tristate "Maxim MAX9286 GMSL deserializer support"
> +	depends on I2C && I2C_MUX
> +	depends on OF
> +	select V4L2_FWNODE
> +	select VIDEO_V4L2_SUBDEV_API
> +	select MEDIA_CONTROLLER
> +	help
> +	  This driver supports the Maxim MAX9286 GMSL deserializer.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called max9286.
> +
>  comment "Video and audio decoders"
>  
>  config VIDEO_SAA717X
> diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
> index 993acab81b2c..c8010d77e1a3 100644
> --- a/drivers/media/i2c/Makefile
> +++ b/drivers/media/i2c/Makefile
> @@ -118,6 +118,7 @@ obj-$(CONFIG_VIDEO_IMX274)	+= imx274.o
>  obj-$(CONFIG_VIDEO_IMX290)	+= imx290.o
>  obj-$(CONFIG_VIDEO_IMX319)	+= imx319.o
>  obj-$(CONFIG_VIDEO_IMX355)	+= imx355.o
> +obj-$(CONFIG_VIDEO_MAX9286)	+= max9286.o
>  obj-$(CONFIG_VIDEO_ST_MIPID02) += st-mipid02.o
>  
>  obj-$(CONFIG_SDR_MAX2175) += max2175.o
> diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
> new file mode 100644
> index 000000000000..47f280518fdb
> --- /dev/null
> +++ b/drivers/media/i2c/max9286.c
> @@ -0,0 +1,1320 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Maxim MAX9286 GMSL Deserializer Driver
> + *
> + * Copyright (C) 2017-2019 Jacopo Mondi
> + * Copyright (C) 2017-2019 Kieran Bingham
> + * Copyright (C) 2017-2019 Laurent Pinchart
> + * Copyright (C) 2017-2019 Niklas Söderlund
> + * Copyright (C) 2016 Renesas Electronics Corporation
> + * Copyright (C) 2015 Cogent Embedded, Inc.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/fwnode.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/gpio/driver.h>
> +#include <linux/i2c.h>
> +#include <linux/i2c-mux.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/of_graph.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/slab.h>
> +
> +#include <media/v4l2-async.h>
> +#include <media/v4l2-ctrls.h>
> +#include <media/v4l2-device.h>
> +#include <media/v4l2-fwnode.h>
> +#include <media/v4l2-subdev.h>
> +
> +/* Register 0x00 */
> +#define MAX9286_MSTLINKSEL_AUTO		(7 << 5)
> +#define MAX9286_MSTLINKSEL(n)		((n) << 5)
> +#define MAX9286_EN_VS_GEN		BIT(4)
> +#define MAX9286_LINKEN(n)		(1 << (n))
> +/* Register 0x01 */
> +#define MAX9286_FSYNCMODE_ECU		(3 << 6)
> +#define MAX9286_FSYNCMODE_EXT		(2 << 6)
> +#define MAX9286_FSYNCMODE_INT_OUT	(1 << 6)
> +#define MAX9286_FSYNCMODE_INT_HIZ	(0 << 6)
> +#define MAX9286_GPIEN			BIT(5)
> +#define MAX9286_ENLMO_RSTFSYNC		BIT(2)
> +#define MAX9286_FSYNCMETH_AUTO		(2 << 0)
> +#define MAX9286_FSYNCMETH_SEMI_AUTO	(1 << 0)
> +#define MAX9286_FSYNCMETH_MANUAL	(0 << 0)
> +#define MAX9286_REG_FSYNC_PERIOD_L	0x06
> +#define MAX9286_REG_FSYNC_PERIOD_M	0x07
> +#define MAX9286_REG_FSYNC_PERIOD_H	0x08
> +/* Register 0x0a */
> +#define MAX9286_FWDCCEN(n)		(1 << ((n) + 4))
> +#define MAX9286_REVCCEN(n)		(1 << (n))
> +/* Register 0x0c */
> +#define MAX9286_HVEN			BIT(7)
> +#define MAX9286_EDC_6BIT_HAMMING	(2 << 5)
> +#define MAX9286_EDC_6BIT_CRC		(1 << 5)
> +#define MAX9286_EDC_1BIT_PARITY		(0 << 5)
> +#define MAX9286_DESEL			BIT(4)
> +#define MAX9286_INVVS			BIT(3)
> +#define MAX9286_INVHS			BIT(2)
> +#define MAX9286_HVSRC_D0		(2 << 0)
> +#define MAX9286_HVSRC_D14		(1 << 0)
> +#define MAX9286_HVSRC_D18		(0 << 0)
> +/* Register 0x0f */
> +#define MAX9286_0X0F_RESERVED		BIT(3)
> +/* Register 0x12 */
> +#define MAX9286_CSILANECNT(n)		(((n) - 1) << 6)
> +#define MAX9286_CSIDBL			BIT(5)
> +#define MAX9286_DBL			BIT(4)
> +#define MAX9286_DATATYPE_USER_8BIT	(11 << 0)
> +#define MAX9286_DATATYPE_USER_YUV_12BIT	(10 << 0)
> +#define MAX9286_DATATYPE_USER_24BIT	(9 << 0)
> +#define MAX9286_DATATYPE_RAW14		(8 << 0)
> +#define MAX9286_DATATYPE_RAW11		(7 << 0)
> +#define MAX9286_DATATYPE_RAW10		(6 << 0)
> +#define MAX9286_DATATYPE_RAW8		(5 << 0)
> +#define MAX9286_DATATYPE_YUV422_10BIT	(4 << 0)
> +#define MAX9286_DATATYPE_YUV422_8BIT	(3 << 0)
> +#define MAX9286_DATATYPE_RGB555		(2 << 0)
> +#define MAX9286_DATATYPE_RGB565		(1 << 0)
> +#define MAX9286_DATATYPE_RGB888		(0 << 0)
> +/* Register 0x15 */
> +#define MAX9286_VC(n)			((n) << 5)
> +#define MAX9286_VCTYPE			BIT(4)
> +#define MAX9286_CSIOUTEN		BIT(3)
> +#define MAX9286_0X15_RESV		(3 << 0)
> +/* Register 0x1b */
> +#define MAX9286_SWITCHIN(n)		(1 << ((n) + 4))
> +#define MAX9286_ENEQ(n)			(1 << (n))
> +/* Register 0x27 */
> +#define MAX9286_LOCKED			BIT(7)
> +/* Register 0x31 */
> +#define MAX9286_FSYNC_LOCKED		BIT(6)
> +/* Register 0x34 */
> +#define MAX9286_I2CLOCACK		BIT(7)
> +#define MAX9286_I2CSLVSH_1046NS_469NS	(3 << 5)
> +#define MAX9286_I2CSLVSH_938NS_352NS	(2 << 5)
> +#define MAX9286_I2CSLVSH_469NS_234NS	(1 << 5)
> +#define MAX9286_I2CSLVSH_352NS_117NS	(0 << 5)
> +#define MAX9286_I2CMSTBT_837KBPS	(7 << 2)
> +#define MAX9286_I2CMSTBT_533KBPS	(6 << 2)
> +#define MAX9286_I2CMSTBT_339KBPS	(5 << 2)
> +#define MAX9286_I2CMSTBT_173KBPS	(4 << 2)
> +#define MAX9286_I2CMSTBT_105KBPS	(3 << 2)
> +#define MAX9286_I2CMSTBT_84KBPS		(2 << 2)
> +#define MAX9286_I2CMSTBT_28KBPS		(1 << 2)
> +#define MAX9286_I2CMSTBT_8KBPS		(0 << 2)
> +#define MAX9286_I2CSLVTO_NONE		(3 << 0)
> +#define MAX9286_I2CSLVTO_1024US		(2 << 0)
> +#define MAX9286_I2CSLVTO_256US		(1 << 0)
> +#define MAX9286_I2CSLVTO_64US		(0 << 0)
> +/* Register 0x3b */
> +#define MAX9286_REV_TRF(n)		((n) << 4)
> +#define MAX9286_REV_AMP(n)		((((n) - 30) / 10) << 1) /* in mV */
> +#define MAX9286_REV_AMP_X		BIT(0)
> +/* Register 0x3f */
> +#define MAX9286_EN_REV_CFG		BIT(6)
> +#define MAX9286_REV_FLEN(n)		((n) - 20)
> +/* Register 0x49 */
> +#define MAX9286_VIDEO_DETECT_MASK	0x0f
> +/* Register 0x69 */
> +#define MAX9286_LFLTBMONMASKED		BIT(7)
> +#define MAX9286_LOCKMONMASKED		BIT(6)
> +#define MAX9286_AUTOCOMBACKEN		BIT(5)
> +#define MAX9286_AUTOMASKEN		BIT(4)
> +#define MAX9286_MASKLINK(n)		((n) << 0)
> +
> +/*
> + * The sink and source pads are created to match the OF graph port numbers so
> + * that their indexes can be used interchangeably.
> + */
> +#define MAX9286_NUM_GMSL		4
> +#define MAX9286_N_SINKS			4
> +#define MAX9286_N_PADS			5
> +#define MAX9286_SRC_PAD			4
> +
> +struct max9286_source {
> +	struct v4l2_async_subdev asd;
> +	struct v4l2_subdev *sd;
> +	struct fwnode_handle *fwnode;
> +};
> +
> +#define asd_to_max9286_source(_asd) \
> +	container_of(_asd, struct max9286_source, asd)
> +
> +struct max9286_priv {
> +	struct i2c_client *client;
> +	struct gpio_desc *gpiod_pwdn;
> +	struct v4l2_subdev sd;
> +	struct media_pad pads[MAX9286_N_PADS];
> +	struct regulator *regulator;
> +
> +	struct gpio_chip gpio;
> +	u8 gpio_state;
> +
> +	struct i2c_mux_core *mux;
> +	unsigned int mux_channel;
> +	bool mux_open;
> +
> +	struct v4l2_ctrl_handler ctrls;
> +	struct v4l2_ctrl *pixelrate;
> +
> +	struct v4l2_mbus_framefmt fmt[MAX9286_N_SINKS];
> +
> +	/* Protects controls and fmt structures */
> +	struct mutex mutex;
> +
> +	unsigned int nsources;
> +	unsigned int source_mask;
> +	unsigned int route_mask;
> +	unsigned int bound_sources;
> +	unsigned int csi2_data_lanes;
> +	struct max9286_source sources[MAX9286_NUM_GMSL];
> +	struct v4l2_async_notifier notifier;
> +};
> +
> +static struct max9286_source *next_source(struct max9286_priv *priv,
> +					  struct max9286_source *source)
> +{
> +	if (!source)
> +		source = &priv->sources[0];
> +	else
> +		source++;
> +
> +	for (; source < &priv->sources[MAX9286_NUM_GMSL]; source++) {
> +		if (source->fwnode)
> +			return source;
> +	}
> +
> +	return NULL;
> +}
> +
> +#define for_each_source(priv, source) \
> +	for ((source) = NULL; ((source) = next_source((priv), (source))); )
> +
> +#define to_index(priv, source) ((source) - &(priv)->sources[0])
> +
> +static inline struct max9286_priv *sd_to_max9286(struct v4l2_subdev *sd)
> +{
> +	return container_of(sd, struct max9286_priv, sd);
> +}
> +
> +/* -----------------------------------------------------------------------------
> + * I2C IO
> + */
> +
> +static int max9286_read(struct max9286_priv *priv, u8 reg)
> +{
> +	int ret;
> +
> +	ret = i2c_smbus_read_byte_data(priv->client, reg);
> +	if (ret < 0)
> +		dev_err(&priv->client->dev,
> +			"%s: register 0x%02x read failed (%d)\n",
> +			__func__, reg, ret);
> +
> +	return ret;
> +}
> +
> +static int max9286_write(struct max9286_priv *priv, u8 reg, u8 val)
> +{
> +	int ret;
> +
> +	ret = i2c_smbus_write_byte_data(priv->client, reg, val);
> +	if (ret < 0)
> +		dev_err(&priv->client->dev,
> +			"%s: register 0x%02x write failed (%d)\n",
> +			__func__, reg, ret);
> +
> +	return ret;
> +}
> +
> +/* -----------------------------------------------------------------------------
> + * I2C Multiplexer
> + */
> +
> +static void max9286_i2c_mux_configure(struct max9286_priv *priv, u8 conf)
> +{
> +	max9286_write(priv, 0x0a, conf);
> +
> +	/*
> +	 * We must sleep after any change to the forward or reverse channel
> +	 * configuration.
> +	 */
> +	usleep_range(3000, 5000);
> +}
> +
> +static void max9286_i2c_mux_open(struct max9286_priv *priv)
> +{
> +	/* Open all channels on the MAX9286 */
> +	max9286_i2c_mux_configure(priv, 0xff);
> +
> +	priv->mux_open = true;
> +}
> +
> +static void max9286_i2c_mux_close(struct max9286_priv *priv)
> +{
> +	/*
> +	 * Ensure that both the forward and reverse channel are disabled on the
> +	 * mux, and that the channel ID is invalidated to ensure we reconfigure
> +	 * on the next max9286_i2c_mux_select() call.
> +	 */
> +	max9286_i2c_mux_configure(priv, 0x00);
> +
> +	priv->mux_open = false;
> +	priv->mux_channel = -1;
> +}
> +
> +static int max9286_i2c_mux_select(struct i2c_mux_core *muxc, u32 chan)
> +{
> +	struct max9286_priv *priv = i2c_mux_priv(muxc);
> +
> +	/* Channel select is disabled when configured in the opened state. */
> +	if (priv->mux_open)
> +		return 0;
> +
> +	if (priv->mux_channel == chan)
> +		return 0;
> +
> +	priv->mux_channel = chan;
> +
> +	max9286_i2c_mux_configure(priv,
> +				  MAX9286_FWDCCEN(chan) |
> +				  MAX9286_REVCCEN(chan));
> +
> +	return 0;
> +}
> +
> +static int max9286_i2c_mux_init(struct max9286_priv *priv)
> +{
> +	struct max9286_source *source;
> +	int ret;
> +
> +	if (!i2c_check_functionality(priv->client->adapter,
> +				     I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
> +		return -ENODEV;
> +
> +	priv->mux = i2c_mux_alloc(priv->client->adapter, &priv->client->dev,
> +				  priv->nsources, 0, I2C_MUX_LOCKED,
> +				  max9286_i2c_mux_select, NULL);
> +	if (!priv->mux)
> +		return -ENOMEM;
> +
> +	priv->mux->priv = priv;
> +
> +	for_each_source(priv, source) {
> +		unsigned int index = to_index(priv, source);
> +
> +		ret = i2c_mux_add_adapter(priv->mux, 0, index, 0);
> +		if (ret < 0)
> +			goto error;
> +	}
> +
> +	return 0;
> +
> +error:
> +	i2c_mux_del_adapters(priv->mux);
> +	return ret;
> +}
> +
> +static void max9286_configure_i2c(struct max9286_priv *priv, bool localack)
> +{
> +	u8 config = MAX9286_I2CSLVSH_469NS_234NS | MAX9286_I2CSLVTO_1024US |
> +		    MAX9286_I2CMSTBT_105KBPS;
> +
> +	if (localack)
> +		config |= MAX9286_I2CLOCACK;
> +
> +	max9286_write(priv, 0x34, config);
> +	usleep_range(3000, 5000);
> +}
> +
> +/*
> + * max9286_check_video_links() - Make sure video links are detected and locked
> + *
> + * Performs safety checks on video link status. Make sure they are detected
> + * and all enabled links are locked.
> + *
> + * Returns 0 for success, -EIO for errors.
> + */
> +static int max9286_check_video_links(struct max9286_priv *priv)
> +{
> +	unsigned int i;
> +	int ret;
> +
> +	/*
> +	 * Make sure valid video links are detected.
> +	 * The delay is not characterized in de-serializer manual, wait up
> +	 * to 5 ms.
> +	 */
> +	for (i = 0; i < 10; i++) {
> +		ret = max9286_read(priv, 0x49);
> +		if (ret < 0)
> +			return -EIO;
> +
> +		if ((ret & MAX9286_VIDEO_DETECT_MASK) == priv->source_mask)
> +			break;
> +
> +		usleep_range(350, 500);
> +	}
> +
> +	if (i == 10) {
> +		dev_err(&priv->client->dev,
> +			"Unable to detect video links: 0x%02x\n", ret);
> +		return -EIO;
> +	}
> +
> +	/* Make sure all enabled links are locked (4ms max). */
> +	for (i = 0; i < 10; i++) {
> +		ret = max9286_read(priv, 0x27);
> +		if (ret < 0)
> +			return -EIO;
> +
> +		if (ret & MAX9286_LOCKED)
> +			break;
> +
> +		usleep_range(350, 450);
> +	}
> +
> +	if (i == 10) {
> +		dev_err(&priv->client->dev, "Not all enabled links locked\n");
> +		return -EIO;
> +	}
> +
> +	return 0;
> +}
> +
> +/*
> + * max9286_check_config_link() - Detect and wait for configuration links
> + *
> + * Determine if the configuration channel is up and settled for a link.
> + *
> + * Returns 0 for success, -EIO for errors.
> + */
> +static int max9286_check_config_link(struct max9286_priv *priv,
> +				     unsigned int source_mask)
> +{
> +	unsigned int conflink_mask = (source_mask & 0x0f) << 4;
> +	unsigned int i;
> +	int ret;
> +
> +	/*
> +	 * Make sure requested configuration links are detected.
> +	 * The delay is not characterized in the chip manual: wait up
> +	 * to 5 milliseconds.
> +	 */
> +	for (i = 0; i < 10; i++) {
> +		ret = max9286_read(priv, 0x49) & 0xf0;
> +		if (ret < 0)
> +			return -EIO;
> +
> +		if (ret == conflink_mask)
> +			break;
> +
> +		usleep_range(350, 500);
> +	}
> +
> +	if (ret != conflink_mask) {
> +		dev_err(&priv->client->dev,
> +			"Unable to detect configuration links: 0x%02x expected 0x%02x\n",
> +			ret, conflink_mask);
> +		return -EIO;
> +	}
> +
> +	dev_info(&priv->client->dev,
> +		 "Successfully detected configuration links after %u loops: 0x%02x\n",
> +		 i, conflink_mask);
> +
> +	return 0;
> +}
> +
> +/* -----------------------------------------------------------------------------
> + * V4L2 Subdev
> + */
> +
> +static int max9286_set_pixelrate(struct max9286_priv *priv)
> +{
> +	struct max9286_source *source = NULL;
> +	u64 pixelrate = 0;
> +
> +	for_each_source(priv, source) {
> +		struct v4l2_ctrl *ctrl;
> +		u64 source_rate = 0;
> +
> +		/* Pixel rate is mandatory to be reported by sources. */
> +		ctrl = v4l2_ctrl_find(source->sd->ctrl_handler,
> +				      V4L2_CID_PIXEL_RATE);
> +		if (!ctrl) {
> +			pixelrate = 0;
> +			break;
> +		}
> +
> +		/* All source must report the same pixel rate. */
> +		source_rate = v4l2_ctrl_g_ctrl_int64(ctrl);
> +		if (!pixelrate) {
> +			pixelrate = source_rate;
> +		} else if (pixelrate != source_rate) {
> +			dev_err(&priv->client->dev,
> +				"Unable to calculate pixel rate\n");
> +			return -EINVAL;
> +		}
> +	}
> +
> +	if (!pixelrate) {
> +		dev_err(&priv->client->dev,
> +			"No pixel rate control available in sources\n");
> +		return -EINVAL;
> +	}
> +
> +	/*
> +	 * The CSI-2 transmitter pixel rate is the single source rate multiplied
> +	 * by the number of available sources.
> +	 */
> +	return v4l2_ctrl_s_ctrl_int64(priv->pixelrate,
> +				      pixelrate * priv->nsources);
> +}
> +
> +static int max9286_notify_bound(struct v4l2_async_notifier *notifier,
> +				struct v4l2_subdev *subdev,
> +				struct v4l2_async_subdev *asd)
> +{
> +	struct max9286_priv *priv = sd_to_max9286(notifier->sd);
> +	struct max9286_source *source = asd_to_max9286_source(asd);
> +	unsigned int index = to_index(priv, source);
> +	unsigned int src_pad;
> +	int ret;
> +
> +	ret = media_entity_get_fwnode_pad(&subdev->entity,
> +					  source->fwnode,
> +					  MEDIA_PAD_FL_SOURCE);
> +	if (ret < 0) {
> +		dev_err(&priv->client->dev,
> +			"Failed to find pad for %s\n", subdev->name);
> +		return ret;
> +	}
> +
> +	priv->bound_sources |= BIT(index);
> +	source->sd = subdev;
> +	src_pad = ret;
> +
> +	ret = media_create_pad_link(&source->sd->entity, src_pad,
> +				    &priv->sd.entity, index,
> +				    MEDIA_LNK_FL_ENABLED |
> +				    MEDIA_LNK_FL_IMMUTABLE);
> +	if (ret) {
> +		dev_err(&priv->client->dev,
> +			"Unable to link %s:%u -> %s:%u\n",
> +			source->sd->name, src_pad, priv->sd.name, index);
> +		return ret;
> +	}
> +
> +	dev_dbg(&priv->client->dev, "Bound %s pad: %u on index %u\n",
> +		subdev->name, src_pad, index);
> +
> +	/*
> +	 * We can only register v4l2_async_notifiers, which do not provide a
> +	 * means to register a complete callback. bound_sources allows us to
> +	 * identify when all remote serializers have completed their probe.
> +	 */
> +	if (priv->bound_sources != priv->source_mask)
> +		return 0;
> +
> +	/*
> +	 * All enabled sources have probed and enabled their reverse control
> +	 * channels:
> +	 *
> +	 * - Verify all configuration links are properly detected
> +	 * - Disable auto-ack as communication on the control channel are now
> +	 *   stable.
> +	 */
> +	max9286_check_config_link(priv, priv->source_mask);
> +
> +	/*
> +	 * Re-configure I2C with local acknowledge disabled after cameras have
> +	 * probed.
> +	 */
> +	max9286_configure_i2c(priv, false);
> +
> +	return max9286_set_pixelrate(priv);
> +}
> +
> +static void max9286_notify_unbind(struct v4l2_async_notifier *notifier,
> +				  struct v4l2_subdev *subdev,
> +				  struct v4l2_async_subdev *asd)
> +{
> +	struct max9286_priv *priv = sd_to_max9286(notifier->sd);
> +	struct max9286_source *source = asd_to_max9286_source(asd);
> +	unsigned int index = to_index(priv, source);
> +
> +	source->sd = NULL;
> +	priv->bound_sources &= ~BIT(index);
> +}
> +
> +static const struct v4l2_async_notifier_operations max9286_notify_ops = {
> +	.bound = max9286_notify_bound,
> +	.unbind = max9286_notify_unbind,
> +};
> +
> +static int max9286_v4l2_notifier_register(struct max9286_priv *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	struct max9286_source *source = NULL;
> +	int ret;
> +
> +	if (!priv->nsources)
> +		return 0;
> +
> +	v4l2_async_notifier_init(&priv->notifier);
> +
> +	for_each_source(priv, source) {
> +		unsigned int i = to_index(priv, source);
> +
> +		source->asd.match_type = V4L2_ASYNC_MATCH_FWNODE;
> +		source->asd.match.fwnode = source->fwnode;
> +
> +		ret = v4l2_async_notifier_add_subdev(&priv->notifier,
> +						     &source->asd);
> +		if (ret) {
> +			dev_err(dev, "Failed to add subdev for source %d", i);
> +			v4l2_async_notifier_cleanup(&priv->notifier);
> +			return ret;
> +		}
> +
> +		/*
> +		 * Balance the reference counting handled through
> +		 * v4l2_async_notifier_cleanup()
> +		 */
> +		fwnode_handle_get(source->fwnode);
> +	}
> +
> +	priv->notifier.ops = &max9286_notify_ops;
> +
> +	ret = v4l2_async_subdev_notifier_register(&priv->sd, &priv->notifier);
> +	if (ret) {
> +		dev_err(dev, "Failed to register subdev_notifier");
> +		v4l2_async_notifier_cleanup(&priv->notifier);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void max9286_v4l2_notifier_unregister(struct max9286_priv *priv)
> +{
> +	if (!priv->nsources)
> +		return;
> +
> +	v4l2_async_notifier_unregister(&priv->notifier);
> +	v4l2_async_notifier_cleanup(&priv->notifier);
> +}
> +
> +static int max9286_s_stream(struct v4l2_subdev *sd, int enable)
> +{
> +	struct max9286_priv *priv = sd_to_max9286(sd);
> +	struct max9286_source *source;
> +	unsigned int i;
> +	bool sync = false;
> +	int ret;
> +
> +	if (enable) {
> +		/*
> +		 * The frame sync between cameras is transmitted across the
> +		 * reverse channel as GPIO. We must open all channels while
> +		 * streaming to allow this synchronisation signal to be shared.
> +		 */
> +		max9286_i2c_mux_open(priv);
> +
> +		/* Start all cameras. */
> +		for_each_source(priv, source) {
> +			ret = v4l2_subdev_call(source->sd, video, s_stream, 1);
> +			if (ret)
> +				return ret;
> +		}
> +
> +		ret = max9286_check_video_links(priv);
> +		if (ret)
> +			return ret;
> +
> +		/*
> +		 * Wait until frame synchronization is locked.
> +		 *
> +		 * Manual says frame sync locking should take ~6 VTS.
> +		 * From practical experience at least 8 are required. Give
> +		 * 12 complete frames time (~400ms at 30 fps) to achieve frame
> +		 * locking before returning error.
> +		 */
> +		for (i = 0; i < 40; i++) {
> +			if (max9286_read(priv, 0x31) & MAX9286_FSYNC_LOCKED) {
> +				sync = true;
> +				break;
> +			}
> +			usleep_range(9000, 11000);
> +		}
> +
> +		if (!sync) {
> +			dev_err(&priv->client->dev,
> +				"Failed to get frame synchronization\n");
> +			return -EXDEV; /* Invalid cross-device link */
> +		}
> +
> +		/*
> +		 * Enable CSI output, VC set according to link number.
> +		 * Bit 7 must be set (chip manual says it's 0 and reserved).
> +		 */
> +		max9286_write(priv, 0x15, 0x80 | MAX9286_VCTYPE |
> +			      MAX9286_CSIOUTEN | MAX9286_0X15_RESV);
> +	} else {
> +		max9286_write(priv, 0x15, MAX9286_VCTYPE | MAX9286_0X15_RESV);
> +
> +		/* Stop all cameras. */
> +		for_each_source(priv, source)
> +			v4l2_subdev_call(source->sd, video, s_stream, 0);
> +
> +		max9286_i2c_mux_close(priv);
> +	}
> +
> +	return 0;
> +}
> +
> +static int max9286_enum_mbus_code(struct v4l2_subdev *sd,
> +				  struct v4l2_subdev_pad_config *cfg,
> +				  struct v4l2_subdev_mbus_code_enum *code)
> +{
> +	if (code->pad || code->index > 0)
> +		return -EINVAL;
> +
> +	code->code = MEDIA_BUS_FMT_UYVY8_1X16;
> +
> +	return 0;
> +}
> +
> +static struct v4l2_mbus_framefmt *
> +max9286_get_pad_format(struct max9286_priv *priv,
> +		       struct v4l2_subdev_pad_config *cfg,
> +		       unsigned int pad, u32 which)
> +{
> +	switch (which) {
> +	case V4L2_SUBDEV_FORMAT_TRY:
> +		return v4l2_subdev_get_try_format(&priv->sd, cfg, pad);
> +	case V4L2_SUBDEV_FORMAT_ACTIVE:
> +		return &priv->fmt[pad];
> +	default:
> +		return NULL;
> +	}
> +}
> +
> +static int max9286_set_fmt(struct v4l2_subdev *sd,
> +			   struct v4l2_subdev_pad_config *cfg,
> +			   struct v4l2_subdev_format *format)
> +{
> +	struct max9286_priv *priv = sd_to_max9286(sd);
> +	struct v4l2_mbus_framefmt *cfg_fmt;
> +
> +	if (format->pad == MAX9286_SRC_PAD)
> +		return -EINVAL;
> +
> +	/* Refuse non YUV422 formats as we hardcode DT to 8 bit YUV422 */
> +	switch (format->format.code) {
> +	case MEDIA_BUS_FMT_UYVY8_1X16:
> +	case MEDIA_BUS_FMT_VYUY8_1X16:
> +	case MEDIA_BUS_FMT_YUYV8_1X16:
> +	case MEDIA_BUS_FMT_YVYU8_1X16:
> +		break;
> +	default:
> +		format->format.code = MEDIA_BUS_FMT_UYVY8_1X16;
> +		break;
> +	}
> +
> +	cfg_fmt = max9286_get_pad_format(priv, cfg, format->pad, format->which);
> +	if (!cfg_fmt)
> +		return -EINVAL;
> +
> +	mutex_lock(&priv->mutex);
> +	*cfg_fmt = format->format;
> +	mutex_unlock(&priv->mutex);
> +
> +	return 0;
> +}
> +
> +static int max9286_get_fmt(struct v4l2_subdev *sd,
> +			   struct v4l2_subdev_pad_config *cfg,
> +			   struct v4l2_subdev_format *format)
> +{
> +	struct max9286_priv *priv = sd_to_max9286(sd);
> +	struct v4l2_mbus_framefmt *cfg_fmt;
> +	unsigned int pad = format->pad;
> +
> +	/*
> +	 * Multiplexed Stream Support: Support link validation by returning the
> +	 * format of the first bound link. All links must have the same format,
> +	 * as we do not support mixing and matching of cameras connected to the
> +	 * max9286.
> +	 */
> +	if (pad == MAX9286_SRC_PAD)
> +		pad = __ffs(priv->bound_sources);
> +
> +	cfg_fmt = max9286_get_pad_format(priv, cfg, pad, format->which);
> +	if (!cfg_fmt)
> +		return -EINVAL;
> +
> +	mutex_lock(&priv->mutex);
> +	format->format = *cfg_fmt;
> +	mutex_unlock(&priv->mutex);
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_subdev_video_ops max9286_video_ops = {
> +	.s_stream	= max9286_s_stream,
> +};
> +
> +static const struct v4l2_subdev_pad_ops max9286_pad_ops = {
> +	.enum_mbus_code = max9286_enum_mbus_code,
> +	.get_fmt	= max9286_get_fmt,
> +	.set_fmt	= max9286_set_fmt,
> +};
> +
> +static const struct v4l2_subdev_ops max9286_subdev_ops = {
> +	.video		= &max9286_video_ops,
> +	.pad		= &max9286_pad_ops,
> +};
> +
> +static void max9286_init_format(struct v4l2_mbus_framefmt *fmt)
> +{
> +	fmt->width		= 1280;
> +	fmt->height		= 800;
> +	fmt->code		= MEDIA_BUS_FMT_UYVY8_1X16;
> +	fmt->colorspace		= V4L2_COLORSPACE_SRGB;
> +	fmt->field		= V4L2_FIELD_NONE;
> +	fmt->ycbcr_enc		= V4L2_YCBCR_ENC_DEFAULT;
> +	fmt->quantization	= V4L2_QUANTIZATION_DEFAULT;
> +	fmt->xfer_func		= V4L2_XFER_FUNC_DEFAULT;
> +}
> +
> +static int max9286_open(struct v4l2_subdev *subdev, struct v4l2_subdev_fh *fh)
> +{
> +	struct v4l2_mbus_framefmt *format;
> +	unsigned int i;
> +
> +	for (i = 0; i < MAX9286_N_SINKS; i++) {
> +		format = v4l2_subdev_get_try_format(subdev, fh->pad, i);
> +		max9286_init_format(format);
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_subdev_internal_ops max9286_subdev_internal_ops = {
> +	.open = max9286_open,
> +};
> +
> +static int max9286_s_ctrl(struct v4l2_ctrl *ctrl)
> +{
> +	switch (ctrl->id) {
> +	case V4L2_CID_PIXEL_RATE:
> +		return 0;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct v4l2_ctrl_ops max9286_ctrl_ops = {
> +	.s_ctrl = max9286_s_ctrl,
> +};
> +
> +static int max9286_v4l2_register(struct max9286_priv *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	struct fwnode_handle *ep;
> +	int ret;
> +	int i;
> +
> +	/* Register v4l2 async notifiers for connected Camera subdevices */
> +	ret = max9286_v4l2_notifier_register(priv);
> +	if (ret) {
> +		dev_err(dev, "Unable to register V4L2 async notifiers\n");
> +		return ret;
> +	}
> +
> +	/* Configure V4L2 for the MAX9286 itself */
> +
> +	for (i = 0; i < MAX9286_N_SINKS; i++)
> +		max9286_init_format(&priv->fmt[i]);
> +
> +	v4l2_i2c_subdev_init(&priv->sd, priv->client, &max9286_subdev_ops);
> +	priv->sd.internal_ops = &max9286_subdev_internal_ops;
> +	priv->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> +
> +	v4l2_ctrl_handler_init(&priv->ctrls, 1);
> +	priv->pixelrate = v4l2_ctrl_new_std(&priv->ctrls,
> +					    &max9286_ctrl_ops,
> +					    V4L2_CID_PIXEL_RATE,
> +					    1, INT_MAX, 1, 50000000);
> +
> +	priv->sd.ctrl_handler = &priv->ctrls;
> +	ret = priv->ctrls.error;
> +	if (ret)
> +		goto err_async;
> +
> +	priv->sd.entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
> +
> +	priv->pads[MAX9286_SRC_PAD].flags = MEDIA_PAD_FL_SOURCE;
> +	for (i = 0; i < MAX9286_SRC_PAD; i++)
> +		priv->pads[i].flags = MEDIA_PAD_FL_SINK;
> +	ret = media_entity_pads_init(&priv->sd.entity, MAX9286_N_PADS,
> +				     priv->pads);
> +	if (ret)
> +		goto err_async;
> +
> +	ep = fwnode_graph_get_endpoint_by_id(dev_fwnode(dev), MAX9286_SRC_PAD,
> +					     0, 0);
> +	if (!ep) {
> +		dev_err(dev, "Unable to retrieve endpoint on \"port@4\"\n");
> +		ret = -ENOENT;
> +		goto err_async;
> +	}
> +	priv->sd.fwnode = ep;
> +
> +	ret = v4l2_async_register_subdev(&priv->sd);
> +	if (ret < 0) {
> +		dev_err(dev, "Unable to register subdevice\n");
> +		goto err_put_node;
> +	}
> +
> +	return 0;
> +
> +err_put_node:
> +	fwnode_handle_put(ep);
> +err_async:
> +	max9286_v4l2_notifier_unregister(priv);
> +
> +	return ret;
> +}
> +
> +static void max9286_v4l2_unregister(struct max9286_priv *priv)
> +{
> +	fwnode_handle_put(priv->sd.fwnode);
> +	v4l2_async_unregister_subdev(&priv->sd);
> +	max9286_v4l2_notifier_unregister(priv);
> +}
> +
> +/* -----------------------------------------------------------------------------
> + * Probe/Remove
> + */
> +
> +static int max9286_setup(struct max9286_priv *priv)
> +{
> +	/*
> +	 * Link ordering values for all enabled links combinations. Orders must
> +	 * be assigned sequentially from 0 to the number of enabled links
> +	 * without leaving any hole for disabled links. We thus assign orders to
> +	 * enabled links first, and use the remaining order values for disabled
> +	 * links are all links must have a different order value;
> +	 */
> +	static const u8 link_order[] = {
> +		(3 << 6) | (2 << 4) | (1 << 2) | (0 << 0), /* xxxx */
> +		(3 << 6) | (2 << 4) | (1 << 2) | (0 << 0), /* xxx0 */
> +		(3 << 6) | (2 << 4) | (0 << 2) | (1 << 0), /* xx0x */
> +		(3 << 6) | (2 << 4) | (1 << 2) | (0 << 0), /* xx10 */
> +		(3 << 6) | (0 << 4) | (2 << 2) | (1 << 0), /* x0xx */
> +		(3 << 6) | (1 << 4) | (2 << 2) | (0 << 0), /* x1x0 */
> +		(3 << 6) | (1 << 4) | (0 << 2) | (2 << 0), /* x10x */
> +		(3 << 6) | (1 << 4) | (1 << 2) | (0 << 0), /* x210 */
> +		(0 << 6) | (3 << 4) | (2 << 2) | (1 << 0), /* 0xxx */
> +		(1 << 6) | (3 << 4) | (2 << 2) | (0 << 0), /* 1xx0 */
> +		(1 << 6) | (3 << 4) | (0 << 2) | (2 << 0), /* 1x0x */
> +		(2 << 6) | (3 << 4) | (1 << 2) | (0 << 0), /* 2x10 */
> +		(1 << 6) | (0 << 4) | (3 << 2) | (2 << 0), /* 10xx */
> +		(2 << 6) | (1 << 4) | (3 << 2) | (0 << 0), /* 21x0 */
> +		(2 << 6) | (1 << 4) | (0 << 2) | (3 << 0), /* 210x */
> +		(3 << 6) | (2 << 4) | (1 << 2) | (0 << 0), /* 3210 */
> +	};
> +
> +	/*
> +	 * Set the I2C bus speed.
> +	 *
> +	 * Enable I2C Local Acknowledge during the probe sequences of the camera
> +	 * only. This should be disabled after the mux is initialised.
> +	 */
> +	max9286_configure_i2c(priv, true);
> +
> +	/*
> +	 * Reverse channel setup.
> +	 *
> +	 * - Enable custom reverse channel configuration (through register 0x3f)
> +	 *   and set the first pulse length to 35 clock cycles.
> +	 * - Increase the reverse channel amplitude to 170mV to accommodate the
> +	 *   high threshold enabled by the serializer driver.
> +	 */
> +	max9286_write(priv, 0x3f, MAX9286_EN_REV_CFG | MAX9286_REV_FLEN(35));
> +	max9286_write(priv, 0x3b, MAX9286_REV_TRF(1) | MAX9286_REV_AMP(70) |
> +		      MAX9286_REV_AMP_X);
> +	usleep_range(2000, 2500);
> +
> +	/*
> +	 * Enable GMSL links, mask unused ones and autodetect link
> +	 * used as CSI clock source.
> +	 */
> +	max9286_write(priv, 0x00, MAX9286_MSTLINKSEL_AUTO | priv->route_mask);
> +	max9286_write(priv, 0x0b, link_order[priv->route_mask]);
> +	max9286_write(priv, 0x69, (0xf & ~priv->route_mask));
> +
> +	/*
> +	 * Video format setup:
> +	 * Disable CSI output, VC is set according to Link number.
> +	 */
> +	max9286_write(priv, 0x15, MAX9286_VCTYPE | MAX9286_0X15_RESV);
> +
> +	/* Enable CSI-2 Lane D0-D3 only, DBL mode, YUV422 8-bit. */
> +	max9286_write(priv, 0x12, MAX9286_CSIDBL | MAX9286_DBL |
> +		      MAX9286_CSILANECNT(priv->csi2_data_lanes) |
> +		      MAX9286_DATATYPE_YUV422_8BIT);
> +
> +	/* Automatic: FRAMESYNC taken from the slowest Link. */
> +	max9286_write(priv, 0x01, MAX9286_FSYNCMODE_INT_HIZ |
> +		      MAX9286_FSYNCMETH_AUTO);
> +
> +	/* Enable HS/VS encoding, use D14/15 for HS/VS, invert VS. */
> +	max9286_write(priv, 0x0c, MAX9286_HVEN | MAX9286_INVVS |
> +		      MAX9286_HVSRC_D14);
> +
> +	/*
> +	 * The overlap window seems to provide additional validation by tracking
> +	 * the delay between vsync and frame sync, generating an error if the
> +	 * delay is bigger than the programmed window, though it's not yet clear
> +	 * what value should be set.
> +	 *
> +	 * As it's an optional value and can be disabled, we do so by setting
> +	 * a 0 overlap value.
> +	 */
> +	max9286_write(priv, 0x63, 0);
> +	max9286_write(priv, 0x64, 0);
> +
> +	/*
> +	 * Wait for 2ms to allow the link to resynchronize after the
> +	 * configuration change.
> +	 */
> +	usleep_range(2000, 5000);
> +
> +	return 0;
> +}
> +
> +static void max9286_gpio_set(struct gpio_chip *chip,
> +			     unsigned int offset, int value)
> +{
> +	struct max9286_priv *priv = gpiochip_get_data(chip);
> +
> +	if (value)
> +		priv->gpio_state |= BIT(offset);
> +	else
> +		priv->gpio_state &= ~BIT(offset);
> +
> +	max9286_write(priv, 0x0f, MAX9286_0X0F_RESERVED | priv->gpio_state);
> +}
> +
> +static int max9286_gpio_get(struct gpio_chip *chip, unsigned int offset)
> +{
> +	struct max9286_priv *priv = gpiochip_get_data(chip);
> +
> +	return priv->gpio_state & BIT(offset);
> +}
> +
> +static int max9286_register_gpio(struct max9286_priv *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	struct gpio_chip *gpio = &priv->gpio;
> +	int ret;
> +
> +	/* Configure the GPIO */
> +	gpio->label = dev_name(dev);
> +	gpio->parent = dev;
> +	gpio->owner = THIS_MODULE;
> +	gpio->of_node = dev->of_node;
> +	gpio->ngpio = 2;
> +	gpio->base = -1;
> +	gpio->set = max9286_gpio_set;
> +	gpio->get = max9286_gpio_get;
> +	gpio->can_sleep = true;
> +
> +	/* GPIO values default to high */
> +	priv->gpio_state = BIT(0) | BIT(1);
> +
> +	ret = devm_gpiochip_add_data(dev, gpio, priv);
> +	if (ret)
> +		dev_err(dev, "Unable to create gpio_chip\n");
> +
> +	return ret;
> +}
> +
> +static int max9286_init(struct device *dev)
> +{
> +	struct max9286_priv *priv;
> +	struct i2c_client *client;
> +	int ret;
> +
> +	client = to_i2c_client(dev);
> +	priv = i2c_get_clientdata(client);
> +
> +	/* Enable the bus power. */
> +	ret = regulator_enable(priv->regulator);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "Unable to turn PoC on\n");
> +		return ret;
> +	}
> +
> +	ret = max9286_setup(priv);
> +	if (ret) {
> +		dev_err(dev, "Unable to setup max9286\n");
> +		goto err_regulator;
> +	}
> +
> +	/*
> +	 * Register all V4L2 interactions for the MAX9286 and notifiers for
> +	 * any subdevices connected.
> +	 */
> +	ret = max9286_v4l2_register(priv);
> +	if (ret) {
> +		dev_err(dev, "Failed to register with V4L2\n");
> +		goto err_regulator;
> +	}
> +
> +	ret = max9286_i2c_mux_init(priv);
> +	if (ret) {
> +		dev_err(dev, "Unable to initialize I2C multiplexer\n");
> +		goto err_v4l2_register;
> +	}
> +
> +	/* Leave the mux channels disabled until they are selected. */
> +	max9286_i2c_mux_close(priv);
> +
> +	return 0;
> +
> +err_v4l2_register:
> +	max9286_v4l2_unregister(priv);
> +err_regulator:
> +	regulator_disable(priv->regulator);
> +
> +	return ret;
> +}
> +
> +static void max9286_cleanup_dt(struct max9286_priv *priv)
> +{
> +	struct max9286_source *source;
> +
> +	for_each_source(priv, source) {
> +		fwnode_handle_put(source->fwnode);
> +		source->fwnode = NULL;
> +	}
> +}
> +
> +static int max9286_parse_dt(struct max9286_priv *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	struct device_node *i2c_mux;
> +	struct device_node *node = NULL;
> +	unsigned int i2c_mux_mask = 0;
> +
> +	/* Balance the of_node_put() performed by of_find_node_by_name(). */
> +	of_node_get(dev->of_node);
> +	i2c_mux = of_find_node_by_name(dev->of_node, "i2c-mux");
> +	if (!i2c_mux) {
> +		dev_err(dev, "Failed to find i2c-mux node\n");
> +		return -EINVAL;
> +	}
> +
> +	/* Identify which i2c-mux channels are enabled */
> +	for_each_child_of_node(i2c_mux, node) {
> +		u32 id = 0;
> +
> +		of_property_read_u32(node, "reg", &id);
> +		if (id >= MAX9286_NUM_GMSL)
> +			continue;
> +
> +		if (!of_device_is_available(node)) {
> +			dev_dbg(dev, "Skipping disabled I2C bus port %u\n", id);
> +			continue;
> +		}
> +
> +		i2c_mux_mask |= BIT(id);
> +	}
> +	of_node_put(node);
> +	of_node_put(i2c_mux);
> +
> +	/* Parse the endpoints */
> +	for_each_endpoint_of_node(dev->of_node, node) {
> +		struct max9286_source *source;
> +		struct of_endpoint ep;
> +
> +		of_graph_parse_endpoint(node, &ep);
> +		dev_dbg(dev, "Endpoint %pOF on port %d",
> +			ep.local_node, ep.port);
> +
> +		if (ep.port > MAX9286_NUM_GMSL) {
> +			dev_err(dev, "Invalid endpoint %s on port %d",
> +				of_node_full_name(ep.local_node), ep.port);
> +			continue;
> +		}
> +
> +		/* For the source endpoint just parse the bus configuration. */
> +		if (ep.port == MAX9286_SRC_PAD) {
> +			struct v4l2_fwnode_endpoint vep = {
> +				.bus_type = V4L2_MBUS_CSI2_DPHY
> +			};
> +			int ret;
> +
> +			ret = v4l2_fwnode_endpoint_parse(
> +					of_fwnode_handle(node), &vep);
> +			if (ret) {
> +				of_node_put(node);
> +				return ret;
> +			}
> +
> +			priv->csi2_data_lanes =
> +				vep.bus.mipi_csi2.num_data_lanes;
> +
> +			continue;
> +		}
> +
> +		/* Skip if the corresponding GMSL link is unavailable. */
> +		if (!(i2c_mux_mask & BIT(ep.port)))
> +			continue;
> +
> +		if (priv->sources[ep.port].fwnode) {
> +			dev_err(dev,
> +				"Multiple port endpoints are not supported: %d",
> +				ep.port);
> +
> +			continue;
> +		}
> +
> +		source = &priv->sources[ep.port];
> +		source->fwnode = fwnode_graph_get_remote_endpoint(
> +						of_fwnode_handle(node));
> +		if (!source->fwnode) {
> +			dev_err(dev,
> +				"Endpoint %pOF has no remote endpoint connection\n",
> +				ep.local_node);
> +
> +			continue;
> +		}
> +
> +		priv->source_mask |= BIT(ep.port);
> +		priv->nsources++;
> +	}
> +	of_node_put(node);
> +
> +	priv->route_mask = priv->source_mask;
> +
> +	return 0;
> +}
> +
> +static int max9286_probe(struct i2c_client *client)
> +{
> +	struct max9286_priv *priv;
> +	int ret;
> +
> +	priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	mutex_init(&priv->mutex);
> +
> +	priv->client = client;
> +	i2c_set_clientdata(client, priv);
> +
> +	priv->gpiod_pwdn = devm_gpiod_get_optional(&client->dev, "enable",
> +						   GPIOD_OUT_HIGH);
> +	if (IS_ERR(priv->gpiod_pwdn))
> +		return PTR_ERR(priv->gpiod_pwdn);
> +
> +	gpiod_set_consumer_name(priv->gpiod_pwdn, "max9286-pwdn");
> +	gpiod_set_value_cansleep(priv->gpiod_pwdn, 1);
> +
> +	/* Wait at least 4ms before the I2C lines latch to the address */
> +	if (priv->gpiod_pwdn)
> +		usleep_range(4000, 5000);
> +
> +	/*
> +	 * The MAX9286 starts by default with all ports enabled, we disable all
> +	 * ports early to ensure that all channels are disabled if we error out
> +	 * and keep the bus consistent.
> +	 */
> +	max9286_i2c_mux_close(priv);
> +
> +	/*
> +	 * The MAX9286 initialises with auto-acknowledge enabled by default.
> +	 * This can be invasive to other transactions on the same bus, so
> +	 * disable it early. It will be enabled only as and when needed.
> +	 */
> +	max9286_configure_i2c(priv, false);
> +
> +	ret = max9286_register_gpio(priv);
> +	if (ret)
> +		goto err_powerdown;
> +
> +	priv->regulator = devm_regulator_get(&client->dev, "poc");
> +	if (IS_ERR(priv->regulator)) {
> +		if (PTR_ERR(priv->regulator) != -EPROBE_DEFER)
> +			dev_err(&client->dev,
> +				"Unable to get PoC regulator (%ld)\n",
> +				PTR_ERR(priv->regulator));
> +		ret = PTR_ERR(priv->regulator);
> +		goto err_powerdown;
> +	}
> +
> +	ret = max9286_parse_dt(priv);
> +	if (ret)
> +		goto err_powerdown;
> +
> +	ret = max9286_init(&client->dev);
> +	if (ret < 0)
> +		goto err_cleanup_dt;
> +
> +	return 0;
> +
> +err_cleanup_dt:
> +	max9286_cleanup_dt(priv);
> +err_powerdown:
> +	gpiod_set_value_cansleep(priv->gpiod_pwdn, 0);
> +
> +	return ret;
> +}
> +
> +static int max9286_remove(struct i2c_client *client)
> +{
> +	struct max9286_priv *priv = i2c_get_clientdata(client);
> +
> +	i2c_mux_del_adapters(priv->mux);
> +
> +	max9286_v4l2_unregister(priv);
> +
> +	regulator_disable(priv->regulator);
> +
> +	gpiod_set_value_cansleep(priv->gpiod_pwdn, 0);
> +
> +	max9286_cleanup_dt(priv);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id max9286_dt_ids[] = {
> +	{ .compatible = "maxim,max9286" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, max9286_dt_ids);
> +
> +static struct i2c_driver max9286_i2c_driver = {
> +	.driver	= {
> +		.name		= "max9286",
> +		.of_match_table	= of_match_ptr(max9286_dt_ids),
> +	},
> +	.probe_new	= max9286_probe,
> +	.remove		= max9286_remove,
> +};
> +
> +module_i2c_driver(max9286_i2c_driver);
> +
> +MODULE_DESCRIPTION("Maxim MAX9286 GMSL Deserializer Driver");
> +MODULE_AUTHOR("Jacopo Mondi, Kieran Bingham, Laurent Pinchart, Niklas Söderlund, Vladimir Barinov");
> +MODULE_LICENSE("GPL");
>
Sakari Ailus July 23, 2020, 10:28 p.m. UTC | #3
Hi Kieran,

On Thu, Jul 16, 2020 at 10:02:24AM +0100, Kieran Bingham wrote:
> Hi Sakari,
> 
> This is the output of checkpatch --strict on this driver. Sorry for not
> detailing this in the commit or cover letter.

No worries.

> 
> > ./patches/gmsl/v10/v10-0001-dt-bindings-media-i2c-Add-bindings-for-Maxim-Int.patch has style problems, please review.
> > --------------------------------------------------------------
> > ./patches/gmsl/v10/v10-0002-media-i2c-Add-MAX9286-driver.patch
> > --------------------------------------------------------------
> > CHECK: Prefer using the BIT macro
> > #246: FILE: drivers/media/i2c/max9286.c:40:
> > +#define MAX9286_FSYNCMODE_INT_OUT	(1 << 6)
> > 
> > CHECK: Prefer using the BIT macro
> > #251: FILE: drivers/media/i2c/max9286.c:45:
> > +#define MAX9286_FSYNCMETH_SEMI_AUTO	(1 << 0)
> > 
> > CHECK: Prefer using the BIT macro
> > #262: FILE: drivers/media/i2c/max9286.c:56:
> > +#define MAX9286_EDC_6BIT_CRC		(1 << 5)
> > 
> > CHECK: Prefer using the BIT macro
> > #268: FILE: drivers/media/i2c/max9286.c:62:
> > +#define MAX9286_HVSRC_D14		(1 << 0)
> > 
> > CHECK: Prefer using the BIT macro
> > #286: FILE: drivers/media/i2c/max9286.c:80:
> > +#define MAX9286_DATATYPE_RGB565		(1 << 0)
> > 
> > CHECK: Prefer using the BIT macro
> > #304: FILE: drivers/media/i2c/max9286.c:98:
> > +#define MAX9286_I2CSLVSH_469NS_234NS	(1 << 5)
> > 
> > CHECK: Prefer using the BIT macro
> > #312: FILE: drivers/media/i2c/max9286.c:106:
> > +#define MAX9286_I2CMSTBT_28KBPS		(1 << 2)
> > 
> > CHECK: Prefer using the BIT macro
> > #316: FILE: drivers/media/i2c/max9286.c:110:
> > +#define MAX9286_I2CSLVTO_256US		(1 << 0)
> 
> None of those are appropriate to use the BIT() macro, as they are all
> entries of a specific field with a shift, such as:
> 
> #define MAX9286_FSYNCMODE_ECU           (3 << 6)
> #define MAX9286_FSYNCMODE_EXT           (2 << 6)
> #define MAX9286_FSYNCMODE_INT_OUT       (1 << 6)
> #define MAX9286_FSYNCMODE_INT_HIZ       (0 << 6)
> 
> Checkpatch is only picking up on the "1 << x" variant of each entry.

Ideally you should use "1U << x" everywhere. If you happen to have a
register with 31st bit signifying something, mayhem would follow. So the
practice is to make all such definitions unsigned.

> 
> 
> > CHECK: Macro argument reuse 'source' - possible side-effects?
> > #399: FILE: drivers/media/i2c/max9286.c:193:
> > +#define for_each_source(priv, source) \
> > +	for ((source) = NULL; ((source) = next_source((priv), (source))); )
> 
> This warns against possible side effects, but the 're-use' effects are
> desired ;-)
> 
> If you'd prefer this macro to be re-written please let me know.

Works for me. Some warnigns are just not useful. I bet quite a few macros
elsewhere in the kernel would trigger this.

> 
> 
> > CHECK: Lines should not end with a '('
> > #1372: FILE: drivers/media/i2c/max9286.c:1166:
> > +			ret = v4l2_fwnode_endpoint_parse(
> 
> Full code block:
> 
> >                         ret = v4l2_fwnode_endpoint_parse(
> >                                         of_fwnode_handle(node), &vep);
> >                         if (ret) {
> >                                 of_node_put(node);
> >                                 return ret;
> >                         }
> 
> That one is awkward, and I chose to keep it as a lesser evil.
> Of course now that we can officially go up to 120 chars, I could move
> this line up.
> 
> If you'd like this to be moved to a single line now we can go over 80
> chars, please confirm.

I don't mind that. Mauro, any thoughts on this?
Kieran Bingham July 24, 2020, 9:32 a.m. UTC | #4
Hi Sakari,

On 23/07/2020 23:28, Sakari Ailus wrote:
> Hi Kieran,
> 
> On Thu, Jul 16, 2020 at 10:02:24AM +0100, Kieran Bingham wrote:
>> Hi Sakari,
>>
>> This is the output of checkpatch --strict on this driver. Sorry for not
>> detailing this in the commit or cover letter.
> 
> No worries.
> 
>>
>>> ./patches/gmsl/v10/v10-0001-dt-bindings-media-i2c-Add-bindings-for-Maxim-Int.patch has style problems, please review.
>>> --------------------------------------------------------------
>>> ./patches/gmsl/v10/v10-0002-media-i2c-Add-MAX9286-driver.patch
>>> --------------------------------------------------------------
>>> CHECK: Prefer using the BIT macro
>>> #246: FILE: drivers/media/i2c/max9286.c:40:
>>> +#define MAX9286_FSYNCMODE_INT_OUT	(1 << 6)
>>>
>>> CHECK: Prefer using the BIT macro
>>> #251: FILE: drivers/media/i2c/max9286.c:45:
>>> +#define MAX9286_FSYNCMETH_SEMI_AUTO	(1 << 0)
>>>
>>> CHECK: Prefer using the BIT macro
>>> #262: FILE: drivers/media/i2c/max9286.c:56:
>>> +#define MAX9286_EDC_6BIT_CRC		(1 << 5)
>>>
>>> CHECK: Prefer using the BIT macro
>>> #268: FILE: drivers/media/i2c/max9286.c:62:
>>> +#define MAX9286_HVSRC_D14		(1 << 0)
>>>
>>> CHECK: Prefer using the BIT macro
>>> #286: FILE: drivers/media/i2c/max9286.c:80:
>>> +#define MAX9286_DATATYPE_RGB565		(1 << 0)
>>>
>>> CHECK: Prefer using the BIT macro
>>> #304: FILE: drivers/media/i2c/max9286.c:98:
>>> +#define MAX9286_I2CSLVSH_469NS_234NS	(1 << 5)
>>>
>>> CHECK: Prefer using the BIT macro
>>> #312: FILE: drivers/media/i2c/max9286.c:106:
>>> +#define MAX9286_I2CMSTBT_28KBPS		(1 << 2)
>>>
>>> CHECK: Prefer using the BIT macro
>>> #316: FILE: drivers/media/i2c/max9286.c:110:
>>> +#define MAX9286_I2CSLVTO_256US		(1 << 0)
>>
>> None of those are appropriate to use the BIT() macro, as they are all
>> entries of a specific field with a shift, such as:
>>
>> #define MAX9286_FSYNCMODE_ECU           (3 << 6)
>> #define MAX9286_FSYNCMODE_EXT           (2 << 6)
>> #define MAX9286_FSYNCMODE_INT_OUT       (1 << 6)
>> #define MAX9286_FSYNCMODE_INT_HIZ       (0 << 6)
>>
>> Checkpatch is only picking up on the "1 << x" variant of each entry.
> 
> Ideally you should use "1U << x" everywhere. If you happen to have a
> register with 31st bit signifying something, mayhem would follow. So the
> practice is to make all such definitions unsigned.

Just to clarify, because of the location you've put your x, which is not
the variable in the above case.

These definitions are possible field values with a shift (enum << y),
not bit values (1 << x)

They can of course be unsigned though.

Is your statement that you would like to see these as:

 #define MAX9286_FSYNCMODE_ECU           (3U << 6)
 #define MAX9286_FSYNCMODE_EXT           (2U << 6)
 #define MAX9286_FSYNCMODE_INT_OUT       (1U << 6)
 #define MAX9286_FSYNCMODE_INT_HIZ       (0U << 6)


Or that you would prefer a macro'ised version:

#define FIELD_ENTRY(value, shift) (value U << shift)


Or rather, I could just convert them all to use FIELD_PREP:

#define MAX9286_FSYNCMODE GENMASK(7,6)

#define MAX9286_FSYNCMODE_ECU      FIELD_PREP(MAX9286_FSYNCMODE, 3)
#define MAX9286_FSYNCMODE_EXT      FIELD_PREP(MAX9286_FSYNCMODE, 2)
#define MAX9286_FSYNCMODE_INT_OUT  FIELD_PREP(MAX9286_FSYNCMODE, 1)
#define MAX9286_FSYNCMODE_INT_HIZ  FIELD_PREP(MAX9286_FSYNCMODE, 0)

If you want me to change these entries, I suspect moving wholly to use
FIELD_PREP/FIELD_GET throughout the driver would be the best course of
action.

A bit of churn, but I can do that if you wish.

--
Kieran



>>> CHECK: Macro argument reuse 'source' - possible side-effects?
>>> #399: FILE: drivers/media/i2c/max9286.c:193:
>>> +#define for_each_source(priv, source) \
>>> +	for ((source) = NULL; ((source) = next_source((priv), (source))); )
>>
>> This warns against possible side effects, but the 're-use' effects are
>> desired ;-)
>>
>> If you'd prefer this macro to be re-written please let me know.
> 
> Works for me. Some warnigns are just not useful. I bet quite a few macros
> elsewhere in the kernel would trigger this.


I think we'll just leave this one ;-)


>>> CHECK: Lines should not end with a '('
>>> #1372: FILE: drivers/media/i2c/max9286.c:1166:
>>> +			ret = v4l2_fwnode_endpoint_parse(
>>
>> Full code block:
>>
>>>                         ret = v4l2_fwnode_endpoint_parse(
>>>                                         of_fwnode_handle(node), &vep);
>>>                         if (ret) {
>>>                                 of_node_put(node);
>>>                                 return ret;
>>>                         }
>>
>> That one is awkward, and I chose to keep it as a lesser evil.
>> Of course now that we can officially go up to 120 chars, I could move
>> this line up.
>>
>> If you'd like this to be moved to a single line now we can go over 80
>> chars, please confirm.
> 
> I don't mind that. Mauro, any thoughts on this?


And I'll let Mauro decide that as it will impact my line-length choices
in the future ;-)
Sakari Ailus July 25, 2020, 8:47 a.m. UTC | #5
Kieran,

On Fri, Jul 24, 2020 at 10:32:11AM +0100, Kieran Bingham wrote:
> Hi Sakari,
> 
> On 23/07/2020 23:28, Sakari Ailus wrote:
> > Hi Kieran,
> > 
> > On Thu, Jul 16, 2020 at 10:02:24AM +0100, Kieran Bingham wrote:
> >> Hi Sakari,
> >>
> >> This is the output of checkpatch --strict on this driver. Sorry for not
> >> detailing this in the commit or cover letter.
> > 
> > No worries.
> > 
> >>
> >>> ./patches/gmsl/v10/v10-0001-dt-bindings-media-i2c-Add-bindings-for-Maxim-Int.patch has style problems, please review.
> >>> --------------------------------------------------------------
> >>> ./patches/gmsl/v10/v10-0002-media-i2c-Add-MAX9286-driver.patch
> >>> --------------------------------------------------------------
> >>> CHECK: Prefer using the BIT macro
> >>> #246: FILE: drivers/media/i2c/max9286.c:40:
> >>> +#define MAX9286_FSYNCMODE_INT_OUT	(1 << 6)
> >>>
> >>> CHECK: Prefer using the BIT macro
> >>> #251: FILE: drivers/media/i2c/max9286.c:45:
> >>> +#define MAX9286_FSYNCMETH_SEMI_AUTO	(1 << 0)
> >>>
> >>> CHECK: Prefer using the BIT macro
> >>> #262: FILE: drivers/media/i2c/max9286.c:56:
> >>> +#define MAX9286_EDC_6BIT_CRC		(1 << 5)
> >>>
> >>> CHECK: Prefer using the BIT macro
> >>> #268: FILE: drivers/media/i2c/max9286.c:62:
> >>> +#define MAX9286_HVSRC_D14		(1 << 0)
> >>>
> >>> CHECK: Prefer using the BIT macro
> >>> #286: FILE: drivers/media/i2c/max9286.c:80:
> >>> +#define MAX9286_DATATYPE_RGB565		(1 << 0)
> >>>
> >>> CHECK: Prefer using the BIT macro
> >>> #304: FILE: drivers/media/i2c/max9286.c:98:
> >>> +#define MAX9286_I2CSLVSH_469NS_234NS	(1 << 5)
> >>>
> >>> CHECK: Prefer using the BIT macro
> >>> #312: FILE: drivers/media/i2c/max9286.c:106:
> >>> +#define MAX9286_I2CMSTBT_28KBPS		(1 << 2)
> >>>
> >>> CHECK: Prefer using the BIT macro
> >>> #316: FILE: drivers/media/i2c/max9286.c:110:
> >>> +#define MAX9286_I2CSLVTO_256US		(1 << 0)
> >>
> >> None of those are appropriate to use the BIT() macro, as they are all
> >> entries of a specific field with a shift, such as:
> >>
> >> #define MAX9286_FSYNCMODE_ECU           (3 << 6)
> >> #define MAX9286_FSYNCMODE_EXT           (2 << 6)
> >> #define MAX9286_FSYNCMODE_INT_OUT       (1 << 6)
> >> #define MAX9286_FSYNCMODE_INT_HIZ       (0 << 6)
> >>
> >> Checkpatch is only picking up on the "1 << x" variant of each entry.
> > 
> > Ideally you should use "1U << x" everywhere. If you happen to have a
> > register with 31st bit signifying something, mayhem would follow. So the
> > practice is to make all such definitions unsigned.
> 
> Just to clarify, because of the location you've put your x, which is not
> the variable in the above case.
> 
> These definitions are possible field values with a shift (enum << y),
> not bit values (1 << x)
> 
> They can of course be unsigned though.
> 
> Is your statement that you would like to see these as:
> 
>  #define MAX9286_FSYNCMODE_ECU           (3U << 6)
>  #define MAX9286_FSYNCMODE_EXT           (2U << 6)
>  #define MAX9286_FSYNCMODE_INT_OUT       (1U << 6)
>  #define MAX9286_FSYNCMODE_INT_HIZ       (0U << 6)

Yes, please. This avoids shifting a non-zero bit to the 31st position of a
32-bit register.

> 
> 
> Or that you would prefer a macro'ised version:
> 
> #define FIELD_ENTRY(value, shift) (value U << shift)
> 
> 
> Or rather, I could just convert them all to use FIELD_PREP:
> 
> #define MAX9286_FSYNCMODE GENMASK(7,6)
> 
> #define MAX9286_FSYNCMODE_ECU      FIELD_PREP(MAX9286_FSYNCMODE, 3)
> #define MAX9286_FSYNCMODE_EXT      FIELD_PREP(MAX9286_FSYNCMODE, 2)
> #define MAX9286_FSYNCMODE_INT_OUT  FIELD_PREP(MAX9286_FSYNCMODE, 1)
> #define MAX9286_FSYNCMODE_INT_HIZ  FIELD_PREP(MAX9286_FSYNCMODE, 0)
> 
> If you want me to change these entries, I suspect moving wholly to use
> FIELD_PREP/FIELD_GET throughout the driver would be the best course of
> action.
> 
> A bit of churn, but I can do that if you wish.
> 
> --
> Kieran
> 
> 
> 
> >>> CHECK: Macro argument reuse 'source' - possible side-effects?
> >>> #399: FILE: drivers/media/i2c/max9286.c:193:
> >>> +#define for_each_source(priv, source) \
> >>> +	for ((source) = NULL; ((source) = next_source((priv), (source))); )
> >>
> >> This warns against possible side effects, but the 're-use' effects are
> >> desired ;-)
> >>
> >> If you'd prefer this macro to be re-written please let me know.
> > 
> > Works for me. Some warnigns are just not useful. I bet quite a few macros
> > elsewhere in the kernel would trigger this.
> 
> 
> I think we'll just leave this one ;-)
> 
> 
> >>> CHECK: Lines should not end with a '('
> >>> #1372: FILE: drivers/media/i2c/max9286.c:1166:
> >>> +			ret = v4l2_fwnode_endpoint_parse(
> >>
> >> Full code block:
> >>
> >>>                         ret = v4l2_fwnode_endpoint_parse(
> >>>                                         of_fwnode_handle(node), &vep);
> >>>                         if (ret) {
> >>>                                 of_node_put(node);
> >>>                                 return ret;
> >>>                         }
> >>
> >> That one is awkward, and I chose to keep it as a lesser evil.
> >> Of course now that we can officially go up to 120 chars, I could move
> >> this line up.
> >>
> >> If you'd like this to be moved to a single line now we can go over 80
> >> chars, please confirm.
> > 
> > I don't mind that. Mauro, any thoughts on this?
> 
> 
> And I'll let Mauro decide that as it will impact my line-length choices
> in the future ;-)

I think it's actually much better to end a line with opening parenthesis
than have a line longer than 80, but I recognise there are differing
opinions.

My terminal window width is 80 and having more terminals is more useful
than being able to see a rare line over 80 completely.
diff mbox series

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index 791d2a862e41..7534df72033f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10274,6 +10274,16 @@  F:	Documentation/hwmon/max6697.rst
 F:	drivers/hwmon/max6697.c
 F:	include/linux/platform_data/max6697.h
 
+MAX9286 QUAD GMSL DESERIALIZER DRIVER
+M:	Jacopo Mondi <jacopo+renesas@jmondi.org>
+M:	Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
+M:	Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
+M:	Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
+L:	linux-media@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
+F:	drivers/media/i2c/max9286.c
+
 MAX9860 MONO AUDIO VOICE CODEC DRIVER
 M:	Peter Rosin <peda@axentia.se>
 L:	alsa-devel@alsa-project.org (moderated for non-subscribers)
diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
index da11036ad804..0a083407aa3e 100644
--- a/drivers/media/i2c/Kconfig
+++ b/drivers/media/i2c/Kconfig
@@ -464,6 +464,19 @@  config VIDEO_VPX3220
 	  To compile this driver as a module, choose M here: the
 	  module will be called vpx3220.
 
+config VIDEO_MAX9286
+	tristate "Maxim MAX9286 GMSL deserializer support"
+	depends on I2C && I2C_MUX
+	depends on OF
+	select V4L2_FWNODE
+	select VIDEO_V4L2_SUBDEV_API
+	select MEDIA_CONTROLLER
+	help
+	  This driver supports the Maxim MAX9286 GMSL deserializer.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called max9286.
+
 comment "Video and audio decoders"
 
 config VIDEO_SAA717X
diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
index 993acab81b2c..c8010d77e1a3 100644
--- a/drivers/media/i2c/Makefile
+++ b/drivers/media/i2c/Makefile
@@ -118,6 +118,7 @@  obj-$(CONFIG_VIDEO_IMX274)	+= imx274.o
 obj-$(CONFIG_VIDEO_IMX290)	+= imx290.o
 obj-$(CONFIG_VIDEO_IMX319)	+= imx319.o
 obj-$(CONFIG_VIDEO_IMX355)	+= imx355.o
+obj-$(CONFIG_VIDEO_MAX9286)	+= max9286.o
 obj-$(CONFIG_VIDEO_ST_MIPID02) += st-mipid02.o
 
 obj-$(CONFIG_SDR_MAX2175) += max2175.o
diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
new file mode 100644
index 000000000000..47f280518fdb
--- /dev/null
+++ b/drivers/media/i2c/max9286.c
@@ -0,0 +1,1320 @@ 
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Maxim MAX9286 GMSL Deserializer Driver
+ *
+ * Copyright (C) 2017-2019 Jacopo Mondi
+ * Copyright (C) 2017-2019 Kieran Bingham
+ * Copyright (C) 2017-2019 Laurent Pinchart
+ * Copyright (C) 2017-2019 Niklas Söderlund
+ * Copyright (C) 2016 Renesas Electronics Corporation
+ * Copyright (C) 2015 Cogent Embedded, Inc.
+ */
+
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/fwnode.h>
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/driver.h>
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of_graph.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+
+#include <media/v4l2-async.h>
+#include <media/v4l2-ctrls.h>
+#include <media/v4l2-device.h>
+#include <media/v4l2-fwnode.h>
+#include <media/v4l2-subdev.h>
+
+/* Register 0x00 */
+#define MAX9286_MSTLINKSEL_AUTO		(7 << 5)
+#define MAX9286_MSTLINKSEL(n)		((n) << 5)
+#define MAX9286_EN_VS_GEN		BIT(4)
+#define MAX9286_LINKEN(n)		(1 << (n))
+/* Register 0x01 */
+#define MAX9286_FSYNCMODE_ECU		(3 << 6)
+#define MAX9286_FSYNCMODE_EXT		(2 << 6)
+#define MAX9286_FSYNCMODE_INT_OUT	(1 << 6)
+#define MAX9286_FSYNCMODE_INT_HIZ	(0 << 6)
+#define MAX9286_GPIEN			BIT(5)
+#define MAX9286_ENLMO_RSTFSYNC		BIT(2)
+#define MAX9286_FSYNCMETH_AUTO		(2 << 0)
+#define MAX9286_FSYNCMETH_SEMI_AUTO	(1 << 0)
+#define MAX9286_FSYNCMETH_MANUAL	(0 << 0)
+#define MAX9286_REG_FSYNC_PERIOD_L	0x06
+#define MAX9286_REG_FSYNC_PERIOD_M	0x07
+#define MAX9286_REG_FSYNC_PERIOD_H	0x08
+/* Register 0x0a */
+#define MAX9286_FWDCCEN(n)		(1 << ((n) + 4))
+#define MAX9286_REVCCEN(n)		(1 << (n))
+/* Register 0x0c */
+#define MAX9286_HVEN			BIT(7)
+#define MAX9286_EDC_6BIT_HAMMING	(2 << 5)
+#define MAX9286_EDC_6BIT_CRC		(1 << 5)
+#define MAX9286_EDC_1BIT_PARITY		(0 << 5)
+#define MAX9286_DESEL			BIT(4)
+#define MAX9286_INVVS			BIT(3)
+#define MAX9286_INVHS			BIT(2)
+#define MAX9286_HVSRC_D0		(2 << 0)
+#define MAX9286_HVSRC_D14		(1 << 0)
+#define MAX9286_HVSRC_D18		(0 << 0)
+/* Register 0x0f */
+#define MAX9286_0X0F_RESERVED		BIT(3)
+/* Register 0x12 */
+#define MAX9286_CSILANECNT(n)		(((n) - 1) << 6)
+#define MAX9286_CSIDBL			BIT(5)
+#define MAX9286_DBL			BIT(4)
+#define MAX9286_DATATYPE_USER_8BIT	(11 << 0)
+#define MAX9286_DATATYPE_USER_YUV_12BIT	(10 << 0)
+#define MAX9286_DATATYPE_USER_24BIT	(9 << 0)
+#define MAX9286_DATATYPE_RAW14		(8 << 0)
+#define MAX9286_DATATYPE_RAW11		(7 << 0)
+#define MAX9286_DATATYPE_RAW10		(6 << 0)
+#define MAX9286_DATATYPE_RAW8		(5 << 0)
+#define MAX9286_DATATYPE_YUV422_10BIT	(4 << 0)
+#define MAX9286_DATATYPE_YUV422_8BIT	(3 << 0)
+#define MAX9286_DATATYPE_RGB555		(2 << 0)
+#define MAX9286_DATATYPE_RGB565		(1 << 0)
+#define MAX9286_DATATYPE_RGB888		(0 << 0)
+/* Register 0x15 */
+#define MAX9286_VC(n)			((n) << 5)
+#define MAX9286_VCTYPE			BIT(4)
+#define MAX9286_CSIOUTEN		BIT(3)
+#define MAX9286_0X15_RESV		(3 << 0)
+/* Register 0x1b */
+#define MAX9286_SWITCHIN(n)		(1 << ((n) + 4))
+#define MAX9286_ENEQ(n)			(1 << (n))
+/* Register 0x27 */
+#define MAX9286_LOCKED			BIT(7)
+/* Register 0x31 */
+#define MAX9286_FSYNC_LOCKED		BIT(6)
+/* Register 0x34 */
+#define MAX9286_I2CLOCACK		BIT(7)
+#define MAX9286_I2CSLVSH_1046NS_469NS	(3 << 5)
+#define MAX9286_I2CSLVSH_938NS_352NS	(2 << 5)
+#define MAX9286_I2CSLVSH_469NS_234NS	(1 << 5)
+#define MAX9286_I2CSLVSH_352NS_117NS	(0 << 5)
+#define MAX9286_I2CMSTBT_837KBPS	(7 << 2)
+#define MAX9286_I2CMSTBT_533KBPS	(6 << 2)
+#define MAX9286_I2CMSTBT_339KBPS	(5 << 2)
+#define MAX9286_I2CMSTBT_173KBPS	(4 << 2)
+#define MAX9286_I2CMSTBT_105KBPS	(3 << 2)
+#define MAX9286_I2CMSTBT_84KBPS		(2 << 2)
+#define MAX9286_I2CMSTBT_28KBPS		(1 << 2)
+#define MAX9286_I2CMSTBT_8KBPS		(0 << 2)
+#define MAX9286_I2CSLVTO_NONE		(3 << 0)
+#define MAX9286_I2CSLVTO_1024US		(2 << 0)
+#define MAX9286_I2CSLVTO_256US		(1 << 0)
+#define MAX9286_I2CSLVTO_64US		(0 << 0)
+/* Register 0x3b */
+#define MAX9286_REV_TRF(n)		((n) << 4)
+#define MAX9286_REV_AMP(n)		((((n) - 30) / 10) << 1) /* in mV */
+#define MAX9286_REV_AMP_X		BIT(0)
+/* Register 0x3f */
+#define MAX9286_EN_REV_CFG		BIT(6)
+#define MAX9286_REV_FLEN(n)		((n) - 20)
+/* Register 0x49 */
+#define MAX9286_VIDEO_DETECT_MASK	0x0f
+/* Register 0x69 */
+#define MAX9286_LFLTBMONMASKED		BIT(7)
+#define MAX9286_LOCKMONMASKED		BIT(6)
+#define MAX9286_AUTOCOMBACKEN		BIT(5)
+#define MAX9286_AUTOMASKEN		BIT(4)
+#define MAX9286_MASKLINK(n)		((n) << 0)
+
+/*
+ * The sink and source pads are created to match the OF graph port numbers so
+ * that their indexes can be used interchangeably.
+ */
+#define MAX9286_NUM_GMSL		4
+#define MAX9286_N_SINKS			4
+#define MAX9286_N_PADS			5
+#define MAX9286_SRC_PAD			4
+
+struct max9286_source {
+	struct v4l2_async_subdev asd;
+	struct v4l2_subdev *sd;
+	struct fwnode_handle *fwnode;
+};
+
+#define asd_to_max9286_source(_asd) \
+	container_of(_asd, struct max9286_source, asd)
+
+struct max9286_priv {
+	struct i2c_client *client;
+	struct gpio_desc *gpiod_pwdn;
+	struct v4l2_subdev sd;
+	struct media_pad pads[MAX9286_N_PADS];
+	struct regulator *regulator;
+
+	struct gpio_chip gpio;
+	u8 gpio_state;
+
+	struct i2c_mux_core *mux;
+	unsigned int mux_channel;
+	bool mux_open;
+
+	struct v4l2_ctrl_handler ctrls;
+	struct v4l2_ctrl *pixelrate;
+
+	struct v4l2_mbus_framefmt fmt[MAX9286_N_SINKS];
+
+	/* Protects controls and fmt structures */
+	struct mutex mutex;
+
+	unsigned int nsources;
+	unsigned int source_mask;
+	unsigned int route_mask;
+	unsigned int bound_sources;
+	unsigned int csi2_data_lanes;
+	struct max9286_source sources[MAX9286_NUM_GMSL];
+	struct v4l2_async_notifier notifier;
+};
+
+static struct max9286_source *next_source(struct max9286_priv *priv,
+					  struct max9286_source *source)
+{
+	if (!source)
+		source = &priv->sources[0];
+	else
+		source++;
+
+	for (; source < &priv->sources[MAX9286_NUM_GMSL]; source++) {
+		if (source->fwnode)
+			return source;
+	}
+
+	return NULL;
+}
+
+#define for_each_source(priv, source) \
+	for ((source) = NULL; ((source) = next_source((priv), (source))); )
+
+#define to_index(priv, source) ((source) - &(priv)->sources[0])
+
+static inline struct max9286_priv *sd_to_max9286(struct v4l2_subdev *sd)
+{
+	return container_of(sd, struct max9286_priv, sd);
+}
+
+/* -----------------------------------------------------------------------------
+ * I2C IO
+ */
+
+static int max9286_read(struct max9286_priv *priv, u8 reg)
+{
+	int ret;
+
+	ret = i2c_smbus_read_byte_data(priv->client, reg);
+	if (ret < 0)
+		dev_err(&priv->client->dev,
+			"%s: register 0x%02x read failed (%d)\n",
+			__func__, reg, ret);
+
+	return ret;
+}
+
+static int max9286_write(struct max9286_priv *priv, u8 reg, u8 val)
+{
+	int ret;
+
+	ret = i2c_smbus_write_byte_data(priv->client, reg, val);
+	if (ret < 0)
+		dev_err(&priv->client->dev,
+			"%s: register 0x%02x write failed (%d)\n",
+			__func__, reg, ret);
+
+	return ret;
+}
+
+/* -----------------------------------------------------------------------------
+ * I2C Multiplexer
+ */
+
+static void max9286_i2c_mux_configure(struct max9286_priv *priv, u8 conf)
+{
+	max9286_write(priv, 0x0a, conf);
+
+	/*
+	 * We must sleep after any change to the forward or reverse channel
+	 * configuration.
+	 */
+	usleep_range(3000, 5000);
+}
+
+static void max9286_i2c_mux_open(struct max9286_priv *priv)
+{
+	/* Open all channels on the MAX9286 */
+	max9286_i2c_mux_configure(priv, 0xff);
+
+	priv->mux_open = true;
+}
+
+static void max9286_i2c_mux_close(struct max9286_priv *priv)
+{
+	/*
+	 * Ensure that both the forward and reverse channel are disabled on the
+	 * mux, and that the channel ID is invalidated to ensure we reconfigure
+	 * on the next max9286_i2c_mux_select() call.
+	 */
+	max9286_i2c_mux_configure(priv, 0x00);
+
+	priv->mux_open = false;
+	priv->mux_channel = -1;
+}
+
+static int max9286_i2c_mux_select(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct max9286_priv *priv = i2c_mux_priv(muxc);
+
+	/* Channel select is disabled when configured in the opened state. */
+	if (priv->mux_open)
+		return 0;
+
+	if (priv->mux_channel == chan)
+		return 0;
+
+	priv->mux_channel = chan;
+
+	max9286_i2c_mux_configure(priv,
+				  MAX9286_FWDCCEN(chan) |
+				  MAX9286_REVCCEN(chan));
+
+	return 0;
+}
+
+static int max9286_i2c_mux_init(struct max9286_priv *priv)
+{
+	struct max9286_source *source;
+	int ret;
+
+	if (!i2c_check_functionality(priv->client->adapter,
+				     I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
+		return -ENODEV;
+
+	priv->mux = i2c_mux_alloc(priv->client->adapter, &priv->client->dev,
+				  priv->nsources, 0, I2C_MUX_LOCKED,
+				  max9286_i2c_mux_select, NULL);
+	if (!priv->mux)
+		return -ENOMEM;
+
+	priv->mux->priv = priv;
+
+	for_each_source(priv, source) {
+		unsigned int index = to_index(priv, source);
+
+		ret = i2c_mux_add_adapter(priv->mux, 0, index, 0);
+		if (ret < 0)
+			goto error;
+	}
+
+	return 0;
+
+error:
+	i2c_mux_del_adapters(priv->mux);
+	return ret;
+}
+
+static void max9286_configure_i2c(struct max9286_priv *priv, bool localack)
+{
+	u8 config = MAX9286_I2CSLVSH_469NS_234NS | MAX9286_I2CSLVTO_1024US |
+		    MAX9286_I2CMSTBT_105KBPS;
+
+	if (localack)
+		config |= MAX9286_I2CLOCACK;
+
+	max9286_write(priv, 0x34, config);
+	usleep_range(3000, 5000);
+}
+
+/*
+ * max9286_check_video_links() - Make sure video links are detected and locked
+ *
+ * Performs safety checks on video link status. Make sure they are detected
+ * and all enabled links are locked.
+ *
+ * Returns 0 for success, -EIO for errors.
+ */
+static int max9286_check_video_links(struct max9286_priv *priv)
+{
+	unsigned int i;
+	int ret;
+
+	/*
+	 * Make sure valid video links are detected.
+	 * The delay is not characterized in de-serializer manual, wait up
+	 * to 5 ms.
+	 */
+	for (i = 0; i < 10; i++) {
+		ret = max9286_read(priv, 0x49);
+		if (ret < 0)
+			return -EIO;
+
+		if ((ret & MAX9286_VIDEO_DETECT_MASK) == priv->source_mask)
+			break;
+
+		usleep_range(350, 500);
+	}
+
+	if (i == 10) {
+		dev_err(&priv->client->dev,
+			"Unable to detect video links: 0x%02x\n", ret);
+		return -EIO;
+	}
+
+	/* Make sure all enabled links are locked (4ms max). */
+	for (i = 0; i < 10; i++) {
+		ret = max9286_read(priv, 0x27);
+		if (ret < 0)
+			return -EIO;
+
+		if (ret & MAX9286_LOCKED)
+			break;
+
+		usleep_range(350, 450);
+	}
+
+	if (i == 10) {
+		dev_err(&priv->client->dev, "Not all enabled links locked\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+
+/*
+ * max9286_check_config_link() - Detect and wait for configuration links
+ *
+ * Determine if the configuration channel is up and settled for a link.
+ *
+ * Returns 0 for success, -EIO for errors.
+ */
+static int max9286_check_config_link(struct max9286_priv *priv,
+				     unsigned int source_mask)
+{
+	unsigned int conflink_mask = (source_mask & 0x0f) << 4;
+	unsigned int i;
+	int ret;
+
+	/*
+	 * Make sure requested configuration links are detected.
+	 * The delay is not characterized in the chip manual: wait up
+	 * to 5 milliseconds.
+	 */
+	for (i = 0; i < 10; i++) {
+		ret = max9286_read(priv, 0x49) & 0xf0;
+		if (ret < 0)
+			return -EIO;
+
+		if (ret == conflink_mask)
+			break;
+
+		usleep_range(350, 500);
+	}
+
+	if (ret != conflink_mask) {
+		dev_err(&priv->client->dev,
+			"Unable to detect configuration links: 0x%02x expected 0x%02x\n",
+			ret, conflink_mask);
+		return -EIO;
+	}
+
+	dev_info(&priv->client->dev,
+		 "Successfully detected configuration links after %u loops: 0x%02x\n",
+		 i, conflink_mask);
+
+	return 0;
+}
+
+/* -----------------------------------------------------------------------------
+ * V4L2 Subdev
+ */
+
+static int max9286_set_pixelrate(struct max9286_priv *priv)
+{
+	struct max9286_source *source = NULL;
+	u64 pixelrate = 0;
+
+	for_each_source(priv, source) {
+		struct v4l2_ctrl *ctrl;
+		u64 source_rate = 0;
+
+		/* Pixel rate is mandatory to be reported by sources. */
+		ctrl = v4l2_ctrl_find(source->sd->ctrl_handler,
+				      V4L2_CID_PIXEL_RATE);
+		if (!ctrl) {
+			pixelrate = 0;
+			break;
+		}
+
+		/* All source must report the same pixel rate. */
+		source_rate = v4l2_ctrl_g_ctrl_int64(ctrl);
+		if (!pixelrate) {
+			pixelrate = source_rate;
+		} else if (pixelrate != source_rate) {
+			dev_err(&priv->client->dev,
+				"Unable to calculate pixel rate\n");
+			return -EINVAL;
+		}
+	}
+
+	if (!pixelrate) {
+		dev_err(&priv->client->dev,
+			"No pixel rate control available in sources\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * The CSI-2 transmitter pixel rate is the single source rate multiplied
+	 * by the number of available sources.
+	 */
+	return v4l2_ctrl_s_ctrl_int64(priv->pixelrate,
+				      pixelrate * priv->nsources);
+}
+
+static int max9286_notify_bound(struct v4l2_async_notifier *notifier,
+				struct v4l2_subdev *subdev,
+				struct v4l2_async_subdev *asd)
+{
+	struct max9286_priv *priv = sd_to_max9286(notifier->sd);
+	struct max9286_source *source = asd_to_max9286_source(asd);
+	unsigned int index = to_index(priv, source);
+	unsigned int src_pad;
+	int ret;
+
+	ret = media_entity_get_fwnode_pad(&subdev->entity,
+					  source->fwnode,
+					  MEDIA_PAD_FL_SOURCE);
+	if (ret < 0) {
+		dev_err(&priv->client->dev,
+			"Failed to find pad for %s\n", subdev->name);
+		return ret;
+	}
+
+	priv->bound_sources |= BIT(index);
+	source->sd = subdev;
+	src_pad = ret;
+
+	ret = media_create_pad_link(&source->sd->entity, src_pad,
+				    &priv->sd.entity, index,
+				    MEDIA_LNK_FL_ENABLED |
+				    MEDIA_LNK_FL_IMMUTABLE);
+	if (ret) {
+		dev_err(&priv->client->dev,
+			"Unable to link %s:%u -> %s:%u\n",
+			source->sd->name, src_pad, priv->sd.name, index);
+		return ret;
+	}
+
+	dev_dbg(&priv->client->dev, "Bound %s pad: %u on index %u\n",
+		subdev->name, src_pad, index);
+
+	/*
+	 * We can only register v4l2_async_notifiers, which do not provide a
+	 * means to register a complete callback. bound_sources allows us to
+	 * identify when all remote serializers have completed their probe.
+	 */
+	if (priv->bound_sources != priv->source_mask)
+		return 0;
+
+	/*
+	 * All enabled sources have probed and enabled their reverse control
+	 * channels:
+	 *
+	 * - Verify all configuration links are properly detected
+	 * - Disable auto-ack as communication on the control channel are now
+	 *   stable.
+	 */
+	max9286_check_config_link(priv, priv->source_mask);
+
+	/*
+	 * Re-configure I2C with local acknowledge disabled after cameras have
+	 * probed.
+	 */
+	max9286_configure_i2c(priv, false);
+
+	return max9286_set_pixelrate(priv);
+}
+
+static void max9286_notify_unbind(struct v4l2_async_notifier *notifier,
+				  struct v4l2_subdev *subdev,
+				  struct v4l2_async_subdev *asd)
+{
+	struct max9286_priv *priv = sd_to_max9286(notifier->sd);
+	struct max9286_source *source = asd_to_max9286_source(asd);
+	unsigned int index = to_index(priv, source);
+
+	source->sd = NULL;
+	priv->bound_sources &= ~BIT(index);
+}
+
+static const struct v4l2_async_notifier_operations max9286_notify_ops = {
+	.bound = max9286_notify_bound,
+	.unbind = max9286_notify_unbind,
+};
+
+static int max9286_v4l2_notifier_register(struct max9286_priv *priv)
+{
+	struct device *dev = &priv->client->dev;
+	struct max9286_source *source = NULL;
+	int ret;
+
+	if (!priv->nsources)
+		return 0;
+
+	v4l2_async_notifier_init(&priv->notifier);
+
+	for_each_source(priv, source) {
+		unsigned int i = to_index(priv, source);
+
+		source->asd.match_type = V4L2_ASYNC_MATCH_FWNODE;
+		source->asd.match.fwnode = source->fwnode;
+
+		ret = v4l2_async_notifier_add_subdev(&priv->notifier,
+						     &source->asd);
+		if (ret) {
+			dev_err(dev, "Failed to add subdev for source %d", i);
+			v4l2_async_notifier_cleanup(&priv->notifier);
+			return ret;
+		}
+
+		/*
+		 * Balance the reference counting handled through
+		 * v4l2_async_notifier_cleanup()
+		 */
+		fwnode_handle_get(source->fwnode);
+	}
+
+	priv->notifier.ops = &max9286_notify_ops;
+
+	ret = v4l2_async_subdev_notifier_register(&priv->sd, &priv->notifier);
+	if (ret) {
+		dev_err(dev, "Failed to register subdev_notifier");
+		v4l2_async_notifier_cleanup(&priv->notifier);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void max9286_v4l2_notifier_unregister(struct max9286_priv *priv)
+{
+	if (!priv->nsources)
+		return;
+
+	v4l2_async_notifier_unregister(&priv->notifier);
+	v4l2_async_notifier_cleanup(&priv->notifier);
+}
+
+static int max9286_s_stream(struct v4l2_subdev *sd, int enable)
+{
+	struct max9286_priv *priv = sd_to_max9286(sd);
+	struct max9286_source *source;
+	unsigned int i;
+	bool sync = false;
+	int ret;
+
+	if (enable) {
+		/*
+		 * The frame sync between cameras is transmitted across the
+		 * reverse channel as GPIO. We must open all channels while
+		 * streaming to allow this synchronisation signal to be shared.
+		 */
+		max9286_i2c_mux_open(priv);
+
+		/* Start all cameras. */
+		for_each_source(priv, source) {
+			ret = v4l2_subdev_call(source->sd, video, s_stream, 1);
+			if (ret)
+				return ret;
+		}
+
+		ret = max9286_check_video_links(priv);
+		if (ret)
+			return ret;
+
+		/*
+		 * Wait until frame synchronization is locked.
+		 *
+		 * Manual says frame sync locking should take ~6 VTS.
+		 * From practical experience at least 8 are required. Give
+		 * 12 complete frames time (~400ms at 30 fps) to achieve frame
+		 * locking before returning error.
+		 */
+		for (i = 0; i < 40; i++) {
+			if (max9286_read(priv, 0x31) & MAX9286_FSYNC_LOCKED) {
+				sync = true;
+				break;
+			}
+			usleep_range(9000, 11000);
+		}
+
+		if (!sync) {
+			dev_err(&priv->client->dev,
+				"Failed to get frame synchronization\n");
+			return -EXDEV; /* Invalid cross-device link */
+		}
+
+		/*
+		 * Enable CSI output, VC set according to link number.
+		 * Bit 7 must be set (chip manual says it's 0 and reserved).
+		 */
+		max9286_write(priv, 0x15, 0x80 | MAX9286_VCTYPE |
+			      MAX9286_CSIOUTEN | MAX9286_0X15_RESV);
+	} else {
+		max9286_write(priv, 0x15, MAX9286_VCTYPE | MAX9286_0X15_RESV);
+
+		/* Stop all cameras. */
+		for_each_source(priv, source)
+			v4l2_subdev_call(source->sd, video, s_stream, 0);
+
+		max9286_i2c_mux_close(priv);
+	}
+
+	return 0;
+}
+
+static int max9286_enum_mbus_code(struct v4l2_subdev *sd,
+				  struct v4l2_subdev_pad_config *cfg,
+				  struct v4l2_subdev_mbus_code_enum *code)
+{
+	if (code->pad || code->index > 0)
+		return -EINVAL;
+
+	code->code = MEDIA_BUS_FMT_UYVY8_1X16;
+
+	return 0;
+}
+
+static struct v4l2_mbus_framefmt *
+max9286_get_pad_format(struct max9286_priv *priv,
+		       struct v4l2_subdev_pad_config *cfg,
+		       unsigned int pad, u32 which)
+{
+	switch (which) {
+	case V4L2_SUBDEV_FORMAT_TRY:
+		return v4l2_subdev_get_try_format(&priv->sd, cfg, pad);
+	case V4L2_SUBDEV_FORMAT_ACTIVE:
+		return &priv->fmt[pad];
+	default:
+		return NULL;
+	}
+}
+
+static int max9286_set_fmt(struct v4l2_subdev *sd,
+			   struct v4l2_subdev_pad_config *cfg,
+			   struct v4l2_subdev_format *format)
+{
+	struct max9286_priv *priv = sd_to_max9286(sd);
+	struct v4l2_mbus_framefmt *cfg_fmt;
+
+	if (format->pad == MAX9286_SRC_PAD)
+		return -EINVAL;
+
+	/* Refuse non YUV422 formats as we hardcode DT to 8 bit YUV422 */
+	switch (format->format.code) {
+	case MEDIA_BUS_FMT_UYVY8_1X16:
+	case MEDIA_BUS_FMT_VYUY8_1X16:
+	case MEDIA_BUS_FMT_YUYV8_1X16:
+	case MEDIA_BUS_FMT_YVYU8_1X16:
+		break;
+	default:
+		format->format.code = MEDIA_BUS_FMT_UYVY8_1X16;
+		break;
+	}
+
+	cfg_fmt = max9286_get_pad_format(priv, cfg, format->pad, format->which);
+	if (!cfg_fmt)
+		return -EINVAL;
+
+	mutex_lock(&priv->mutex);
+	*cfg_fmt = format->format;
+	mutex_unlock(&priv->mutex);
+
+	return 0;
+}
+
+static int max9286_get_fmt(struct v4l2_subdev *sd,
+			   struct v4l2_subdev_pad_config *cfg,
+			   struct v4l2_subdev_format *format)
+{
+	struct max9286_priv *priv = sd_to_max9286(sd);
+	struct v4l2_mbus_framefmt *cfg_fmt;
+	unsigned int pad = format->pad;
+
+	/*
+	 * Multiplexed Stream Support: Support link validation by returning the
+	 * format of the first bound link. All links must have the same format,
+	 * as we do not support mixing and matching of cameras connected to the
+	 * max9286.
+	 */
+	if (pad == MAX9286_SRC_PAD)
+		pad = __ffs(priv->bound_sources);
+
+	cfg_fmt = max9286_get_pad_format(priv, cfg, pad, format->which);
+	if (!cfg_fmt)
+		return -EINVAL;
+
+	mutex_lock(&priv->mutex);
+	format->format = *cfg_fmt;
+	mutex_unlock(&priv->mutex);
+
+	return 0;
+}
+
+static const struct v4l2_subdev_video_ops max9286_video_ops = {
+	.s_stream	= max9286_s_stream,
+};
+
+static const struct v4l2_subdev_pad_ops max9286_pad_ops = {
+	.enum_mbus_code = max9286_enum_mbus_code,
+	.get_fmt	= max9286_get_fmt,
+	.set_fmt	= max9286_set_fmt,
+};
+
+static const struct v4l2_subdev_ops max9286_subdev_ops = {
+	.video		= &max9286_video_ops,
+	.pad		= &max9286_pad_ops,
+};
+
+static void max9286_init_format(struct v4l2_mbus_framefmt *fmt)
+{
+	fmt->width		= 1280;
+	fmt->height		= 800;
+	fmt->code		= MEDIA_BUS_FMT_UYVY8_1X16;
+	fmt->colorspace		= V4L2_COLORSPACE_SRGB;
+	fmt->field		= V4L2_FIELD_NONE;
+	fmt->ycbcr_enc		= V4L2_YCBCR_ENC_DEFAULT;
+	fmt->quantization	= V4L2_QUANTIZATION_DEFAULT;
+	fmt->xfer_func		= V4L2_XFER_FUNC_DEFAULT;
+}
+
+static int max9286_open(struct v4l2_subdev *subdev, struct v4l2_subdev_fh *fh)
+{
+	struct v4l2_mbus_framefmt *format;
+	unsigned int i;
+
+	for (i = 0; i < MAX9286_N_SINKS; i++) {
+		format = v4l2_subdev_get_try_format(subdev, fh->pad, i);
+		max9286_init_format(format);
+	}
+
+	return 0;
+}
+
+static const struct v4l2_subdev_internal_ops max9286_subdev_internal_ops = {
+	.open = max9286_open,
+};
+
+static int max9286_s_ctrl(struct v4l2_ctrl *ctrl)
+{
+	switch (ctrl->id) {
+	case V4L2_CID_PIXEL_RATE:
+		return 0;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct v4l2_ctrl_ops max9286_ctrl_ops = {
+	.s_ctrl = max9286_s_ctrl,
+};
+
+static int max9286_v4l2_register(struct max9286_priv *priv)
+{
+	struct device *dev = &priv->client->dev;
+	struct fwnode_handle *ep;
+	int ret;
+	int i;
+
+	/* Register v4l2 async notifiers for connected Camera subdevices */
+	ret = max9286_v4l2_notifier_register(priv);
+	if (ret) {
+		dev_err(dev, "Unable to register V4L2 async notifiers\n");
+		return ret;
+	}
+
+	/* Configure V4L2 for the MAX9286 itself */
+
+	for (i = 0; i < MAX9286_N_SINKS; i++)
+		max9286_init_format(&priv->fmt[i]);
+
+	v4l2_i2c_subdev_init(&priv->sd, priv->client, &max9286_subdev_ops);
+	priv->sd.internal_ops = &max9286_subdev_internal_ops;
+	priv->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
+
+	v4l2_ctrl_handler_init(&priv->ctrls, 1);
+	priv->pixelrate = v4l2_ctrl_new_std(&priv->ctrls,
+					    &max9286_ctrl_ops,
+					    V4L2_CID_PIXEL_RATE,
+					    1, INT_MAX, 1, 50000000);
+
+	priv->sd.ctrl_handler = &priv->ctrls;
+	ret = priv->ctrls.error;
+	if (ret)
+		goto err_async;
+
+	priv->sd.entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
+
+	priv->pads[MAX9286_SRC_PAD].flags = MEDIA_PAD_FL_SOURCE;
+	for (i = 0; i < MAX9286_SRC_PAD; i++)
+		priv->pads[i].flags = MEDIA_PAD_FL_SINK;
+	ret = media_entity_pads_init(&priv->sd.entity, MAX9286_N_PADS,
+				     priv->pads);
+	if (ret)
+		goto err_async;
+
+	ep = fwnode_graph_get_endpoint_by_id(dev_fwnode(dev), MAX9286_SRC_PAD,
+					     0, 0);
+	if (!ep) {
+		dev_err(dev, "Unable to retrieve endpoint on \"port@4\"\n");
+		ret = -ENOENT;
+		goto err_async;
+	}
+	priv->sd.fwnode = ep;
+
+	ret = v4l2_async_register_subdev(&priv->sd);
+	if (ret < 0) {
+		dev_err(dev, "Unable to register subdevice\n");
+		goto err_put_node;
+	}
+
+	return 0;
+
+err_put_node:
+	fwnode_handle_put(ep);
+err_async:
+	max9286_v4l2_notifier_unregister(priv);
+
+	return ret;
+}
+
+static void max9286_v4l2_unregister(struct max9286_priv *priv)
+{
+	fwnode_handle_put(priv->sd.fwnode);
+	v4l2_async_unregister_subdev(&priv->sd);
+	max9286_v4l2_notifier_unregister(priv);
+}
+
+/* -----------------------------------------------------------------------------
+ * Probe/Remove
+ */
+
+static int max9286_setup(struct max9286_priv *priv)
+{
+	/*
+	 * Link ordering values for all enabled links combinations. Orders must
+	 * be assigned sequentially from 0 to the number of enabled links
+	 * without leaving any hole for disabled links. We thus assign orders to
+	 * enabled links first, and use the remaining order values for disabled
+	 * links are all links must have a different order value;
+	 */
+	static const u8 link_order[] = {
+		(3 << 6) | (2 << 4) | (1 << 2) | (0 << 0), /* xxxx */
+		(3 << 6) | (2 << 4) | (1 << 2) | (0 << 0), /* xxx0 */
+		(3 << 6) | (2 << 4) | (0 << 2) | (1 << 0), /* xx0x */
+		(3 << 6) | (2 << 4) | (1 << 2) | (0 << 0), /* xx10 */
+		(3 << 6) | (0 << 4) | (2 << 2) | (1 << 0), /* x0xx */
+		(3 << 6) | (1 << 4) | (2 << 2) | (0 << 0), /* x1x0 */
+		(3 << 6) | (1 << 4) | (0 << 2) | (2 << 0), /* x10x */
+		(3 << 6) | (1 << 4) | (1 << 2) | (0 << 0), /* x210 */
+		(0 << 6) | (3 << 4) | (2 << 2) | (1 << 0), /* 0xxx */
+		(1 << 6) | (3 << 4) | (2 << 2) | (0 << 0), /* 1xx0 */
+		(1 << 6) | (3 << 4) | (0 << 2) | (2 << 0), /* 1x0x */
+		(2 << 6) | (3 << 4) | (1 << 2) | (0 << 0), /* 2x10 */
+		(1 << 6) | (0 << 4) | (3 << 2) | (2 << 0), /* 10xx */
+		(2 << 6) | (1 << 4) | (3 << 2) | (0 << 0), /* 21x0 */
+		(2 << 6) | (1 << 4) | (0 << 2) | (3 << 0), /* 210x */
+		(3 << 6) | (2 << 4) | (1 << 2) | (0 << 0), /* 3210 */
+	};
+
+	/*
+	 * Set the I2C bus speed.
+	 *
+	 * Enable I2C Local Acknowledge during the probe sequences of the camera
+	 * only. This should be disabled after the mux is initialised.
+	 */
+	max9286_configure_i2c(priv, true);
+
+	/*
+	 * Reverse channel setup.
+	 *
+	 * - Enable custom reverse channel configuration (through register 0x3f)
+	 *   and set the first pulse length to 35 clock cycles.
+	 * - Increase the reverse channel amplitude to 170mV to accommodate the
+	 *   high threshold enabled by the serializer driver.
+	 */
+	max9286_write(priv, 0x3f, MAX9286_EN_REV_CFG | MAX9286_REV_FLEN(35));
+	max9286_write(priv, 0x3b, MAX9286_REV_TRF(1) | MAX9286_REV_AMP(70) |
+		      MAX9286_REV_AMP_X);
+	usleep_range(2000, 2500);
+
+	/*
+	 * Enable GMSL links, mask unused ones and autodetect link
+	 * used as CSI clock source.
+	 */
+	max9286_write(priv, 0x00, MAX9286_MSTLINKSEL_AUTO | priv->route_mask);
+	max9286_write(priv, 0x0b, link_order[priv->route_mask]);
+	max9286_write(priv, 0x69, (0xf & ~priv->route_mask));
+
+	/*
+	 * Video format setup:
+	 * Disable CSI output, VC is set according to Link number.
+	 */
+	max9286_write(priv, 0x15, MAX9286_VCTYPE | MAX9286_0X15_RESV);
+
+	/* Enable CSI-2 Lane D0-D3 only, DBL mode, YUV422 8-bit. */
+	max9286_write(priv, 0x12, MAX9286_CSIDBL | MAX9286_DBL |
+		      MAX9286_CSILANECNT(priv->csi2_data_lanes) |
+		      MAX9286_DATATYPE_YUV422_8BIT);
+
+	/* Automatic: FRAMESYNC taken from the slowest Link. */
+	max9286_write(priv, 0x01, MAX9286_FSYNCMODE_INT_HIZ |
+		      MAX9286_FSYNCMETH_AUTO);
+
+	/* Enable HS/VS encoding, use D14/15 for HS/VS, invert VS. */
+	max9286_write(priv, 0x0c, MAX9286_HVEN | MAX9286_INVVS |
+		      MAX9286_HVSRC_D14);
+
+	/*
+	 * The overlap window seems to provide additional validation by tracking
+	 * the delay between vsync and frame sync, generating an error if the
+	 * delay is bigger than the programmed window, though it's not yet clear
+	 * what value should be set.
+	 *
+	 * As it's an optional value and can be disabled, we do so by setting
+	 * a 0 overlap value.
+	 */
+	max9286_write(priv, 0x63, 0);
+	max9286_write(priv, 0x64, 0);
+
+	/*
+	 * Wait for 2ms to allow the link to resynchronize after the
+	 * configuration change.
+	 */
+	usleep_range(2000, 5000);
+
+	return 0;
+}
+
+static void max9286_gpio_set(struct gpio_chip *chip,
+			     unsigned int offset, int value)
+{
+	struct max9286_priv *priv = gpiochip_get_data(chip);
+
+	if (value)
+		priv->gpio_state |= BIT(offset);
+	else
+		priv->gpio_state &= ~BIT(offset);
+
+	max9286_write(priv, 0x0f, MAX9286_0X0F_RESERVED | priv->gpio_state);
+}
+
+static int max9286_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+	struct max9286_priv *priv = gpiochip_get_data(chip);
+
+	return priv->gpio_state & BIT(offset);
+}
+
+static int max9286_register_gpio(struct max9286_priv *priv)
+{
+	struct device *dev = &priv->client->dev;
+	struct gpio_chip *gpio = &priv->gpio;
+	int ret;
+
+	/* Configure the GPIO */
+	gpio->label = dev_name(dev);
+	gpio->parent = dev;
+	gpio->owner = THIS_MODULE;
+	gpio->of_node = dev->of_node;
+	gpio->ngpio = 2;
+	gpio->base = -1;
+	gpio->set = max9286_gpio_set;
+	gpio->get = max9286_gpio_get;
+	gpio->can_sleep = true;
+
+	/* GPIO values default to high */
+	priv->gpio_state = BIT(0) | BIT(1);
+
+	ret = devm_gpiochip_add_data(dev, gpio, priv);
+	if (ret)
+		dev_err(dev, "Unable to create gpio_chip\n");
+
+	return ret;
+}
+
+static int max9286_init(struct device *dev)
+{
+	struct max9286_priv *priv;
+	struct i2c_client *client;
+	int ret;
+
+	client = to_i2c_client(dev);
+	priv = i2c_get_clientdata(client);
+
+	/* Enable the bus power. */
+	ret = regulator_enable(priv->regulator);
+	if (ret < 0) {
+		dev_err(&client->dev, "Unable to turn PoC on\n");
+		return ret;
+	}
+
+	ret = max9286_setup(priv);
+	if (ret) {
+		dev_err(dev, "Unable to setup max9286\n");
+		goto err_regulator;
+	}
+
+	/*
+	 * Register all V4L2 interactions for the MAX9286 and notifiers for
+	 * any subdevices connected.
+	 */
+	ret = max9286_v4l2_register(priv);
+	if (ret) {
+		dev_err(dev, "Failed to register with V4L2\n");
+		goto err_regulator;
+	}
+
+	ret = max9286_i2c_mux_init(priv);
+	if (ret) {
+		dev_err(dev, "Unable to initialize I2C multiplexer\n");
+		goto err_v4l2_register;
+	}
+
+	/* Leave the mux channels disabled until they are selected. */
+	max9286_i2c_mux_close(priv);
+
+	return 0;
+
+err_v4l2_register:
+	max9286_v4l2_unregister(priv);
+err_regulator:
+	regulator_disable(priv->regulator);
+
+	return ret;
+}
+
+static void max9286_cleanup_dt(struct max9286_priv *priv)
+{
+	struct max9286_source *source;
+
+	for_each_source(priv, source) {
+		fwnode_handle_put(source->fwnode);
+		source->fwnode = NULL;
+	}
+}
+
+static int max9286_parse_dt(struct max9286_priv *priv)
+{
+	struct device *dev = &priv->client->dev;
+	struct device_node *i2c_mux;
+	struct device_node *node = NULL;
+	unsigned int i2c_mux_mask = 0;
+
+	/* Balance the of_node_put() performed by of_find_node_by_name(). */
+	of_node_get(dev->of_node);
+	i2c_mux = of_find_node_by_name(dev->of_node, "i2c-mux");
+	if (!i2c_mux) {
+		dev_err(dev, "Failed to find i2c-mux node\n");
+		return -EINVAL;
+	}
+
+	/* Identify which i2c-mux channels are enabled */
+	for_each_child_of_node(i2c_mux, node) {
+		u32 id = 0;
+
+		of_property_read_u32(node, "reg", &id);
+		if (id >= MAX9286_NUM_GMSL)
+			continue;
+
+		if (!of_device_is_available(node)) {
+			dev_dbg(dev, "Skipping disabled I2C bus port %u\n", id);
+			continue;
+		}
+
+		i2c_mux_mask |= BIT(id);
+	}
+	of_node_put(node);
+	of_node_put(i2c_mux);
+
+	/* Parse the endpoints */
+	for_each_endpoint_of_node(dev->of_node, node) {
+		struct max9286_source *source;
+		struct of_endpoint ep;
+
+		of_graph_parse_endpoint(node, &ep);
+		dev_dbg(dev, "Endpoint %pOF on port %d",
+			ep.local_node, ep.port);
+
+		if (ep.port > MAX9286_NUM_GMSL) {
+			dev_err(dev, "Invalid endpoint %s on port %d",
+				of_node_full_name(ep.local_node), ep.port);
+			continue;
+		}
+
+		/* For the source endpoint just parse the bus configuration. */
+		if (ep.port == MAX9286_SRC_PAD) {
+			struct v4l2_fwnode_endpoint vep = {
+				.bus_type = V4L2_MBUS_CSI2_DPHY
+			};
+			int ret;
+
+			ret = v4l2_fwnode_endpoint_parse(
+					of_fwnode_handle(node), &vep);
+			if (ret) {
+				of_node_put(node);
+				return ret;
+			}
+
+			priv->csi2_data_lanes =
+				vep.bus.mipi_csi2.num_data_lanes;
+
+			continue;
+		}
+
+		/* Skip if the corresponding GMSL link is unavailable. */
+		if (!(i2c_mux_mask & BIT(ep.port)))
+			continue;
+
+		if (priv->sources[ep.port].fwnode) {
+			dev_err(dev,
+				"Multiple port endpoints are not supported: %d",
+				ep.port);
+
+			continue;
+		}
+
+		source = &priv->sources[ep.port];
+		source->fwnode = fwnode_graph_get_remote_endpoint(
+						of_fwnode_handle(node));
+		if (!source->fwnode) {
+			dev_err(dev,
+				"Endpoint %pOF has no remote endpoint connection\n",
+				ep.local_node);
+
+			continue;
+		}
+
+		priv->source_mask |= BIT(ep.port);
+		priv->nsources++;
+	}
+	of_node_put(node);
+
+	priv->route_mask = priv->source_mask;
+
+	return 0;
+}
+
+static int max9286_probe(struct i2c_client *client)
+{
+	struct max9286_priv *priv;
+	int ret;
+
+	priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	mutex_init(&priv->mutex);
+
+	priv->client = client;
+	i2c_set_clientdata(client, priv);
+
+	priv->gpiod_pwdn = devm_gpiod_get_optional(&client->dev, "enable",
+						   GPIOD_OUT_HIGH);
+	if (IS_ERR(priv->gpiod_pwdn))
+		return PTR_ERR(priv->gpiod_pwdn);
+
+	gpiod_set_consumer_name(priv->gpiod_pwdn, "max9286-pwdn");
+	gpiod_set_value_cansleep(priv->gpiod_pwdn, 1);
+
+	/* Wait at least 4ms before the I2C lines latch to the address */
+	if (priv->gpiod_pwdn)
+		usleep_range(4000, 5000);
+
+	/*
+	 * The MAX9286 starts by default with all ports enabled, we disable all
+	 * ports early to ensure that all channels are disabled if we error out
+	 * and keep the bus consistent.
+	 */
+	max9286_i2c_mux_close(priv);
+
+	/*
+	 * The MAX9286 initialises with auto-acknowledge enabled by default.
+	 * This can be invasive to other transactions on the same bus, so
+	 * disable it early. It will be enabled only as and when needed.
+	 */
+	max9286_configure_i2c(priv, false);
+
+	ret = max9286_register_gpio(priv);
+	if (ret)
+		goto err_powerdown;
+
+	priv->regulator = devm_regulator_get(&client->dev, "poc");
+	if (IS_ERR(priv->regulator)) {
+		if (PTR_ERR(priv->regulator) != -EPROBE_DEFER)
+			dev_err(&client->dev,
+				"Unable to get PoC regulator (%ld)\n",
+				PTR_ERR(priv->regulator));
+		ret = PTR_ERR(priv->regulator);
+		goto err_powerdown;
+	}
+
+	ret = max9286_parse_dt(priv);
+	if (ret)
+		goto err_powerdown;
+
+	ret = max9286_init(&client->dev);
+	if (ret < 0)
+		goto err_cleanup_dt;
+
+	return 0;
+
+err_cleanup_dt:
+	max9286_cleanup_dt(priv);
+err_powerdown:
+	gpiod_set_value_cansleep(priv->gpiod_pwdn, 0);
+
+	return ret;
+}
+
+static int max9286_remove(struct i2c_client *client)
+{
+	struct max9286_priv *priv = i2c_get_clientdata(client);
+
+	i2c_mux_del_adapters(priv->mux);
+
+	max9286_v4l2_unregister(priv);
+
+	regulator_disable(priv->regulator);
+
+	gpiod_set_value_cansleep(priv->gpiod_pwdn, 0);
+
+	max9286_cleanup_dt(priv);
+
+	return 0;
+}
+
+static const struct of_device_id max9286_dt_ids[] = {
+	{ .compatible = "maxim,max9286" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, max9286_dt_ids);
+
+static struct i2c_driver max9286_i2c_driver = {
+	.driver	= {
+		.name		= "max9286",
+		.of_match_table	= of_match_ptr(max9286_dt_ids),
+	},
+	.probe_new	= max9286_probe,
+	.remove		= max9286_remove,
+};
+
+module_i2c_driver(max9286_i2c_driver);
+
+MODULE_DESCRIPTION("Maxim MAX9286 GMSL Deserializer Driver");
+MODULE_AUTHOR("Jacopo Mondi, Kieran Bingham, Laurent Pinchart, Niklas Söderlund, Vladimir Barinov");
+MODULE_LICENSE("GPL");