dt-bindings: display: tfp410: Add bus parameters properties

The TFP410 supports configuration of several input bus parameters
through either the I2C port or chip pins. In the latter case, we need to
specify those parameters in DT.

Two new properties are added, ti,deskew to specify the data de-skew
configuration (as set through the DK[3:1] pins), and pclk-sample to
specify the pixel clock sampling edge (as set through the EDGE pin).
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Tested-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

Documentation/devicetree/bindings/display/bridge/ti,tfp410.txt

@@ -6,15 +6,25 @@ Required properties:
 
 Optional properties:
 - powerdown-gpios: power-down gpio
-- reg: I2C address. If and only if present the device node
-       should be placed into the i2c controller node where the
-       tfp410 i2c is connected to.
+- reg: I2C address. If and only if present the device node should be placed
+  into the I2C controller node where the TFP410 I2C is connected to.
+- ti,deskew: data de-skew in 350ps increments, from -4 to +3, as configured
+  through th DK[3:1] pins. This property shall be present only if the TFP410
+  is not connected through I2C.
 
 Required nodes:
-- Video port 0 for DPI input [1].
-- Video port 1 for DVI output [1].
 
-[1]: Documentation/devicetree/bindings/media/video-interfaces.txt
+This device has two video ports. Their connections are modeled using the OF
+graph bindings specified in [1]. Each port node shall have a single endpoint.
+
+- Port 0 is the DPI input port. Its endpoint subnode shall contain a
+  pclk-sample property and a remote-endpoint property as specified in [1].
+
+- Port 1 is the DVI output port. Its endpoint subnode shall contain a
+  remote-endpoint property is specified in [1].
+
+[1] Documentation/devicetree/bindings/media/video-interfaces.txt
+
 
 Example
 -------
@@ -22,6 +32,7 @@ Example
 tfp410: encoder@0 {
 	compatible = "ti,tfp410";
 	powerdown-gpios = <&twl_gpio 2 GPIO_ACTIVE_LOW>;
+	ti,deskew = <4>;
 
 	ports {
 		#address-cells = <1>;
@@ -31,6 +42,7 @@ tfp410: encoder@0 {
 			reg = <0>;
 
 			tfp410_in: endpoint@0 {
+				pclk-sample = <1>;
 				remote-endpoint = <&dpi_out>;
 			};
 		};