[PATCH 5/5] drm/bridge: ti-tfp410: Report input bus config through bridge timings

[Laurent Pinchart]

The TFP410 supports configurable pixel clock sampling edge and data
de-skew adjustments. The configuration can be set through I2C or
dedicated chip pins.

Report the configuration through the drm_bridge timings. As the
ti-tftp410 driver doesn't support configuring the chip through I2C, we
simply use the default configuration in that case. When the chip is
configured through dedicated pins, we parse the configuration from DT.

Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
 drivers/gpu/drm/bridge/ti-tfp410.c | 77 ++++++++++++++++++++++++++++--
 1 file changed, 74 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ti-tfp410.c b/drivers/gpu/drm/bridge/ti-tfp410.c
index d25d23cfe3f5..48ec647a7526 100644
--- a/drivers/gpu/drm/bridge/ti-tfp410.c
+++ b/drivers/gpu/drm/bridge/ti-tfp410.c
@@ -34,6 +34,8 @@ struct tfp410 {
 	struct delayed_work	hpd_work;
 	struct gpio_desc	*powerdown;
 
+	struct drm_bridge_timings timings;
+
 	struct device *dev;
 };
 
@@ -180,6 +182,70 @@ static irqreturn_t tfp410_hpd_irq_thread(int irq, void *arg)
 	return IRQ_HANDLED;
 }
 
+static const struct drm_bridge_timings tfp410_default_timings = {
+	.input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE
+			 | DRM_BUS_FLAG_DE_HIGH,
+	.setup_time_ps = 1200,
+	.hold_time_ps = 1300,
+};
+
+static int tfp410_parse_timings(struct tfp410 *dvi, bool i2c)
+{
+	struct drm_bridge_timings *timings = &dvi->timings;
+	struct device_node *ep;
+	u32 pclk_sample = 0;
+	s32 deskew = 0;
+
+	/* Start with defaults. */
+	*timings = tfp410_default_timings;
+
+	if (i2c)
+		/*
+		 * In I2C mode timings are configured through the I2C interface.
+		 * As the driver doesn't support I2C configuration yet, we just
+		 * go with the defaults (BSEL=1, DSEL=1, DKEN=0, EDGE=1).
+		 */
+		return 0;
+
+	/*
+	 * In non-I2C mode, timings are configured through the BSEL, DSEL, DKEN
+	 * and EDGE pins. They are specified in DT through endpoint properties
+	 * and vendor-specific properties.
+	 */
+	ep = of_graph_get_endpoint_by_regs(dvi->dev->of_node, 0, 0);
+	if (!ep)
+		return -EINVAL;
+
+	/* Get the sampling edge from the endpoint. */
+	of_property_read_u32(ep, "pclk-sample", &pclk_sample);
+	of_node_put(ep);
+
+	timings->input_bus_flags = DRM_BUS_FLAG_DE_HIGH;
+
+	switch (pclk_sample) {
+	case 0:
+		timings->input_bus_flags |= DRM_BUS_FLAG_PIXDATA_SAMPLE_NEGEDGE
+					 |  DRM_BUS_FLAG_SYNC_SAMPLE_NEGEDGE;
+		break;
+	case 1:
+		timings->input_bus_flags |= DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE
+					 |  DRM_BUS_FLAG_SYNC_SAMPLE_POSEDGE;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* Get the setup and hold time from vendor-specific properties. */
+	of_property_read_u32(dvi->dev->of_node, "ti,deskew", (u32 *)&deskew);
+	if (deskew < -4 || deskew > 3)
+		return -EINVAL;
+
+	timings->setup_time_ps = min(0, 1200 - 350 * deskew);
+	timings->hold_time_ps = min(0, 1300 + 350 * deskew);
+
+	return 0;
+}
+
 static int tfp410_get_connector_properties(struct tfp410 *dvi)
 {
 	struct device_node *connector_node, *ddc_phandle;
@@ -223,7 +289,7 @@ static int tfp410_get_connector_properties(struct tfp410 *dvi)
 	return ret;
 }
 
-static int tfp410_init(struct device *dev)
+static int tfp410_init(struct device *dev, bool i2c)
 {
 	struct tfp410 *dvi;
 	int ret;
@@ -240,8 +306,13 @@ static int tfp410_init(struct device *dev)
 
 	dvi->bridge.funcs = &tfp410_bridge_funcs;
 	dvi->bridge.of_node = dev->of_node;
+	dvi->bridge.timings = &dvi->timings;
 	dvi->dev = dev;
 
+	ret = tfp410_parse_timings(dvi, i2c);
+	if (ret)
+		goto fail;
+
 	ret = tfp410_get_connector_properties(dvi);
 	if (ret)
 		goto fail;
@@ -294,7 +365,7 @@ static int tfp410_fini(struct device *dev)
 
 static int tfp410_probe(struct platform_device *pdev)
 {
-	return tfp410_init(&pdev->dev);
+	return tfp410_init(&pdev->dev, false);
 }
 
 static int tfp410_remove(struct platform_device *pdev)
@@ -331,7 +402,7 @@ static int tfp410_i2c_probe(struct i2c_client *client,
 		return -ENXIO;
 	}
 
-	return tfp410_init(&client->dev);
+	return tfp410_init(&client->dev, true);
 }
 
 static int tfp410_i2c_remove(struct i2c_client *client)
-- 
Regards,

Laurent Pinchart