diff mbox

[RFC,3/3] drm: bridge: lvds-encoder: on request, override the bus format

Message ID 20180317221525.18534-4-peda@axentia.se (mailing list archive)
State New, archived
Headers show

Commit Message

Peter Rosin March 17, 2018, 10:15 p.m. UTC
If the bridge changes the bus format, allow this to be described in
the bridge, instead of providing false information about the bus
format of the panel itself.

Signed-off-by: Peter Rosin <peda@axentia.se>
---
 .../bindings/display/bridge/lvds-transmitter.txt       |  8 ++++++++
 drivers/gpu/drm/bridge/lvds-encoder.c                  | 18 ++++++++++++++++++
 2 files changed, 26 insertions(+)

Comments

Laurent Pinchart March 20, 2018, 2 p.m. UTC | #1
Hi Peter,

Thank you for the patch.

On Sunday, 18 March 2018 00:15:25 EET Peter Rosin wrote:
> If the bridge changes the bus format, allow this to be described in
> the bridge, instead of providing false information about the bus
> format of the panel itself.
> 
> Signed-off-by: Peter Rosin <peda@axentia.se>
> ---
>  .../bindings/display/bridge/lvds-transmitter.txt       |  8 ++++++++
>  drivers/gpu/drm/bridge/lvds-encoder.c                  | 18 +++++++++++++++
>  2 files changed, 26 insertions(+)
> 
> diff --git
> a/Documentation/devicetree/bindings/display/bridge/lvds-transmitter.txt
> b/Documentation/devicetree/bindings/display/bridge/lvds-transmitter.txt
> index 9d09190d9210..c0fbe74272e7 100644
> --- a/Documentation/devicetree/bindings/display/bridge/lvds-transmitter.txt
> +++ b/Documentation/devicetree/bindings/display/bridge/lvds-transmitter.txt
> @@ -29,6 +29,14 @@ Required properties:
> 
>  	      "ti,ds90c185"
> 
> +Optional properties:
> +
> +- interface-pix-fmt:
> +	      Override the bus format of the panel, in case the bridge
> +	      converts the signals. Recognized formats include:
> +
> +	      "rgb565"

Please describe the format in more details, with an explicit mapping of bits 
to signals, otherwise we'll end up again with multiple different 
interpretations (at least when it comes to endianness).

> +
>  Required nodes:
> 
>  This device has two video ports. Their connections are modeled using the OF
> diff --git a/drivers/gpu/drm/bridge/lvds-encoder.c
> b/drivers/gpu/drm/bridge/lvds-encoder.c index 75b0d3f6e4de..acff3a5b0562
> 100644
> --- a/drivers/gpu/drm/bridge/lvds-encoder.c
> +++ b/drivers/gpu/drm/bridge/lvds-encoder.c
> @@ -39,6 +39,9 @@ static int lvds_encoder_probe(struct platform_device
> *pdev) struct device_node *panel_node;
>  	struct drm_panel *panel;
>  	struct lvds_encoder *lvds_encoder;
> +	u32 bus_format = 0;
> +	const char *fmt;
> +	int ret;
> 
>  	lvds_encoder = devm_kzalloc(&pdev->dev, sizeof(*lvds_encoder),
>  				    GFP_KERNEL);
> @@ -79,6 +82,21 @@ static int lvds_encoder_probe(struct platform_device
> *pdev) if (IS_ERR(lvds_encoder->panel_bridge))
>  		return PTR_ERR(lvds_encoder->panel_bridge);
> 
> +	ret = of_property_read_string(pdev->dev.of_node,
> +				      "interface-pix-fmt", &fmt);
> +	if (!ret) {
> +		if (!strcmp(fmt, "rgb565")) {
> +			bus_format = MEDIA_BUS_FMT_RGB565_1X16;

I think the string to fourcc conversion should take place in the DRM core, not 
in the LVDS encoder driver. This would avoid ending up with multiple 
incompatible conversions. It might even be better to move the DT parsing to 
the core as well, not just the conversion.

> +		} else {
> +			dev_dbg(&pdev->dev,
> +				"requested interface-pix-fmt not recognized\n");
> +			return -EINVAL;
> +		}
> +	}
> +	if (bus_format)
> +		drm_panel_bridge_set_bus_format(lvds_encoder->panel_bridge,
> +						bus_format);
> +
>  	/* The panel_bridge bridge is attached to the panel's of_node,
>  	 * but we need a bridge attached to our of_node for our user
>  	 * to look up.
diff mbox

Patch

diff --git a/Documentation/devicetree/bindings/display/bridge/lvds-transmitter.txt b/Documentation/devicetree/bindings/display/bridge/lvds-transmitter.txt
index 9d09190d9210..c0fbe74272e7 100644
--- a/Documentation/devicetree/bindings/display/bridge/lvds-transmitter.txt
+++ b/Documentation/devicetree/bindings/display/bridge/lvds-transmitter.txt
@@ -29,6 +29,14 @@  Required properties:
 
 	      "ti,ds90c185"
 
+Optional properties:
+
+- interface-pix-fmt:
+	      Override the bus format of the panel, in case the bridge
+	      converts the signals. Recognized formats include:
+
+	      "rgb565"
+
 Required nodes:
 
 This device has two video ports. Their connections are modeled using the OF
diff --git a/drivers/gpu/drm/bridge/lvds-encoder.c b/drivers/gpu/drm/bridge/lvds-encoder.c
index 75b0d3f6e4de..acff3a5b0562 100644
--- a/drivers/gpu/drm/bridge/lvds-encoder.c
+++ b/drivers/gpu/drm/bridge/lvds-encoder.c
@@ -39,6 +39,9 @@  static int lvds_encoder_probe(struct platform_device *pdev)
 	struct device_node *panel_node;
 	struct drm_panel *panel;
 	struct lvds_encoder *lvds_encoder;
+	u32 bus_format = 0;
+	const char *fmt;
+	int ret;
 
 	lvds_encoder = devm_kzalloc(&pdev->dev, sizeof(*lvds_encoder),
 				    GFP_KERNEL);
@@ -79,6 +82,21 @@  static int lvds_encoder_probe(struct platform_device *pdev)
 	if (IS_ERR(lvds_encoder->panel_bridge))
 		return PTR_ERR(lvds_encoder->panel_bridge);
 
+	ret = of_property_read_string(pdev->dev.of_node,
+				      "interface-pix-fmt", &fmt);
+	if (!ret) {
+		if (!strcmp(fmt, "rgb565")) {
+			bus_format = MEDIA_BUS_FMT_RGB565_1X16;
+		} else {
+			dev_dbg(&pdev->dev,
+				"requested interface-pix-fmt not recognized\n");
+			return -EINVAL;
+		}
+	}
+	if (bus_format)
+		drm_panel_bridge_set_bus_format(lvds_encoder->panel_bridge,
+						bus_format);
+
 	/* The panel_bridge bridge is attached to the panel's of_node,
 	 * but we need a bridge attached to our of_node for our user
 	 * to look up.