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

[Sean Paul <seanpaul@chromium.org>]

On Thu, Jan 18, 2018 at 10:23:55AM +0530, Archit Taneja wrote:
> 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 <architt@codeaurora.org>

Reviewed-by: Sean Paul <seanpaul@chromium.org>

> ---
> 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>;
> +				};
> +			};
> +		};
> +	};
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> hosted by The Linux Foundation
> 

-- 
Sean Paul, Software Engineer, Google / Chromium OS
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