[PATCH V4 1/2] dt-bindings: display: bridge: lvds-codec: Document pixel data sampling edge select

The OnSemi FIN3385 Parallel-to-LVDS encoder has a dedicated input line to
select input pixel data sampling edge. Add DT property "pclk-sample", not
the same as the one used by display timings but rather the same as used by
media, to define the pixel data sampling edge.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Alexandre Torgue <redacted>
Cc: Andrzej Hajda <redacted>
Cc: Antonio Borneo <redacted>
Cc: Benjamin Gaignard <redacted>
Cc: Biju Das <biju.das.jz@bp.renesas.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Philippe Cornu <redacted>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Sam Ravnborg <redacted>
Cc: Vincent Abriou <redacted>
Cc: Yannick Fertre <redacted>
Cc: devicetree@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-stm32@st-md-mailman.stormreply.com
To: dri-devel@lists.freedesktop.org
---
V4: New patch split from combined V3
---
 .../bindings/display/bridge/lvds-codec.yaml    | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/bridge/lvds-codec.yaml b/Documentation/devicetree/bindings/display/bridge/lvds-codec.yaml
index 304a1367faaa..f4dd16bd69d2 100644
--- a/Documentation/devicetree/bindings/display/bridge/lvds-codec.yaml
+++ b/Documentation/devicetree/bindings/display/bridge/lvds-codec.yaml

@@ -64,6 +64,14 @@ properties:
       - port@0
       - port@1
 
+  pclk-sample:
+    description:
+      Data sampling on rising or falling edge.
+    enum:
+      - 0  # Falling edge
+      - 1  # Rising edge
+    default: 0
+
   powerdown-gpios:
     description:
       The GPIO used to control the power down line of this device.

@@ -71,6 +79,16 @@ properties:
 
   power-supply: true
 
+if:
+  not:
+    properties:
+      compatible:
+        contains:
+          const: lvds-encoder
+then:
+  properties:
+    pclk-sample: false
+
 required:
   - compatible
   - ports

-- 
2.30.2


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The OnSemi FIN3385 Parallel-to-LVDS encoder has a dedicated input line to
select input pixel data sampling edge. Add DT property "pclk-sample", not
the same as the one used by display timings but rather the same as used by
media, and configure bus flags based on this DT property.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Alexandre Torgue <redacted>
Cc: Andrzej Hajda <redacted>
Cc: Antonio Borneo <redacted>
Cc: Benjamin Gaignard <redacted>
Cc: Biju Das <biju.das.jz@bp.renesas.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Philippe Cornu <redacted>
Cc: Sam Ravnborg <redacted>
Cc: Vincent Abriou <redacted>
Cc: Yannick Fertre <redacted>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-stm32@st-md-mailman.stormreply.com
To: dri-devel@lists.freedesktop.org
---
V2: - Limit the pixelclk-active to encoders only
    - Update DT binding document
V3: - Determine whether this is encoder from connector, i.e.
      lvds_codec->connector_type == DRM_MODE_CONNECTOR_LVDS
V4: - Switch to pclk-sample. Note that the value of this is inverted,
      so all the existing users of pixelclk-active using previous
      version of this patch must be reworked
---
 drivers/gpu/drm/bridge/lvds-codec.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/gpu/drm/bridge/lvds-codec.c b/drivers/gpu/drm/bridge/lvds-codec.c
index dcf579a4cf83..8a7cb267ab14 100644
--- a/drivers/gpu/drm/bridge/lvds-codec.c
+++ b/drivers/gpu/drm/bridge/lvds-codec.c

@@ -19,6 +19,7 @@ struct lvds_codec {
 	struct device *dev;
 	struct drm_bridge bridge;
 	struct drm_bridge *panel_bridge;
+	struct drm_bridge_timings timings;
 	struct regulator *vcc;
 	struct gpio_desc *powerdown_gpio;
 	u32 connector_type;

@@ -80,6 +81,7 @@ static int lvds_codec_probe(struct platform_device *pdev)
 	struct device_node *panel_node;
 	struct drm_panel *panel;
 	struct lvds_codec *lvds_codec;
+	u32 val;
 
 	lvds_codec = devm_kzalloc(dev, sizeof(*lvds_codec), GFP_KERNEL);
 	if (!lvds_codec)

@@ -119,6 +121,18 @@ static int lvds_codec_probe(struct platform_device *pdev)
 	if (IS_ERR(lvds_codec->panel_bridge))
 		return PTR_ERR(lvds_codec->panel_bridge);
 
+	/*
+	 * Encoder might sample data on different clock edge than the display,
+	 * for example OnSemi FIN3385 has a dedicated strapping pin to select
+	 * the sampling edge.
+	 */
+	if (lvds_codec->connector_type == DRM_MODE_CONNECTOR_LVDS &&
+	    !of_property_read_u32(dev->of_node, "pclk-sample", &val)) {
+		lvds_codec->timings.input_bus_flags = val ?
+			DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE :
+			DRM_BUS_FLAG_PIXDATA_SAMPLE_NEGEDGE;
+	}
+
 	/*
 	 * 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

@@ -126,6 +140,7 @@ static int lvds_codec_probe(struct platform_device *pdev)
 	 */
 	lvds_codec->bridge.of_node = dev->of_node;
 	lvds_codec->bridge.funcs = &funcs;
+	lvds_codec->bridge.timings = &lvds_codec->timings;
 	drm_bridge_add(&lvds_codec->bridge);
 
 	platform_set_drvdata(pdev, lvds_codec);

-- 
2.30.2


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On Sat, May 15, 2021 at 10:43:15PM +0200, Marek Vasut wrote:

This is already defined in video-interfaces.yaml, why are you redefining 
it here?

It's also defined to be an endpoint property, so move it there and 
reference video-interfaces.yaml.

This constraint would be difficult to express with the property in an 
endpoint. I'd just drop it.

Rob

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