Re: [RFC v2 2/2] dt-bindings: mipi-dsi: Add dual-channel DSI related info

Add binding info for peripherals that support dual-channel DSI. Add
corresponding optional bindings for DSI host controllers that may
be configured in this mode. Add an example of an I2C controlled
device operating in dual-channel DSI mode.

Signed-off-by: Archit Taneja <redacted>
---
v2:
- Specify that clock-master is a boolean property.
- Drop/add unit-address and #*-cells where applicable.

  .../devicetree/bindings/display/mipi-dsi-bus.txt   | 80 ++++++++++++++++++++++
  1 file changed, 80 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/mipi-dsi-bus.txt b/Documentation/devicetree/bindings/display/mipi-dsi-bus.txt
index 94fb72cb916f..7a3abbedb3fa 100644
--- a/Documentation/devicetree/bindings/display/mipi-dsi-bus.txt
+++ b/Documentation/devicetree/bindings/display/mipi-dsi-bus.txt

@@ -29,6 +29,13 @@ Required properties:
  - #size-cells: Should be 0. There are cases where it makes sense to use a
    different value here. See below.
  
+Optional properties:
+- clock-master: boolean. Should be enabled if the host is being used in
+  conjunction with another DSI host to drive the same peripheral. Hardware
+  supporting such a configuration generally requires the data on both the busses
+  to be driven by the same clock. Only the DSI host instance controlling this
+  clock should contain this property.
+
  DSI peripheral
  ==============
  

@@ -62,6 +69,16 @@ primary control bus, but are also connected to a DSI bus (mostly for the data
  path). Connections between such peripherals and a DSI host can be represented
  using the graph bindings [1], [2].
  
+Peripherals that support dual channel DSI
+-----------------------------------------
+
+Peripherals with higher bandwidth requirements can be connected to 2 DSI
+busses. Each DSI bus/channel drives some portion of the pixel data (generally
+left/right half of each line of the display, or even/odd lines of the display).
+The graph bindings should be used to represent the multiple DSI busses that are
+connected to this peripheral. Each DSI host's output endpoint can be linked to
+an input endpoint of the DSI peripheral.
+
  [1] Documentation/devicetree/bindings/graph.txt
  [2] Documentation/devicetree/bindings/media/video-interfaces.txt
  

@@ -71,6 +88,8 @@ Examples
    with different virtual channel configurations.
  - (4) is an example of a peripheral on a I2C control bus connected with to
    a DSI host using of-graph bindings.
+- (5) is an example of 2 DSI hosts driving a dual-channel DSI peripheral,
+  which uses I2C as its primary control bus.
  
  1)
  	dsi-host {

@@ -153,3 +172,64 @@ Examples
  			};
  		};
  	};
+
+5)
+	i2c-host {
+		dsi-bridge@35 {
+			compatible = "...";
+			reg = <0x35>;
+
+			ports {
+				#address-cells = <1>;
+				#size-cells = <0>;
+
+				port@0 {
+					reg = <0>;
+					dsi0_in: endpoint {
+						remote-endpoint = <&dsi0_out>;
+					};
+				};
+
+				port@1 {
+					reg = <1>;
+					dsi1_in: endpoint {
+						remote-endpoint = <&dsi1_out>;
+					};
+				};
+			};
+		};
+	};
+
+	dsi0-host {
+		...
+
+		/*
+		 * this DSI instance drives the clock for both the host
+		 * controllers
+		 */
+		clock-master;
+
+		ports {
+			...
+
+			port {
+				dsi0_out: endpoint {
+					remote-endpoint = <&dsi0_in>;
+				};
+			};
+		};
+	};
+
+	dsi1-host {
+		...
+
+		ports {
+			...
+
+			port {
+				dsi1_out: endpoint {
+					remote-endpoint = <&dsi1_in>;
+				};
+			};
+		};
+	};