Subject: [PATCH V5 2/2] drm/bridge: lvds-codec: Add support for pixel data sampling edge select

From: Marek Vasut <[email-masked]>
Date: Wed, 2 Jun 2021 22:36:08 +0200

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 <[email-masked]>
Cc: Alexandre Torgue <[email-masked]>
Cc: Andrzej Hajda <[email-masked]>
Cc: Antonio Borneo <[email-masked]>
Cc: Benjamin Gaignard <[email-masked]>
Cc: Biju Das <[email-masked]>
Cc: Laurent Pinchart <[email-masked]>
Cc: Maxime Coquelin <[email-masked]>
Cc: Philippe Cornu <[email-masked]>
Cc: Sam Ravnborg <[email-masked]>
Cc: Vincent Abriou <[email-masked]>
Cc: Yannick Fertre <[email-masked]>
Cc: [email-masked]
Cc: [email-masked]
To: [email-masked]
---
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
V5: - Move pclk-sample to endpoint. Again, all existing users of the
      bindings must be reworked
---
 drivers/gpu/drm/bridge/lvds-codec.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/gpu/drm/bridge/lvds-codec.c b/drivers/gpu/drm/bridge/lvds-codec.c
index dcf579a4cf833..80ce6783d10a8 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;
@@ -78,8 +79,10 @@ static int lvds_codec_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct device_node *panel_node;
+	struct device_node *bus_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 +122,27 @@ 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) {
+		bus_node = of_graph_get_endpoint_by_regs(dev->of_node, 0, 0);
+		if (!bus_node) {
+			dev_dbg(dev, "bus DT node not found\n");
+			return -ENXIO;
+		}
+
+		if (!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;
+		}
+
+		of_node_put(bus_node);
+	}
+
 	/*
 	 * 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 +150,7 @@ 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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