Re: [RFC 1/2] dt-bindings: mipi-dsi: Add info about peripherals with non-DSI control bus

[Rob Herring <robh@kernel.org>]

On Tue, Dec 05, 2017 at 04:03:55PM +0530, Archit Taneja wrote:
> Add a section that describes dt-bindings for peripherals that support
> MIPI DSI, but have a different bus as the primary control bus. Add an
> example for such peripherals.
> 
> Signed-off-by: Archit Taneja <architt@codeaurora.org>
> ---
>  .../devicetree/bindings/display/mipi-dsi-bus.txt   | 75 ++++++++++++++++++++--
>  1 file changed, 68 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/display/mipi-dsi-bus.txt b/Documentation/devicetree/bindings/display/mipi-dsi-bus.txt
> index 973c27273772..77a7cec15f5b 100644
> --- a/Documentation/devicetree/bindings/display/mipi-dsi-bus.txt
> +++ b/Documentation/devicetree/bindings/display/mipi-dsi-bus.txt
> @@ -16,7 +16,7 @@ The following assumes that only a single peripheral is connected to a DSI
>  host. Experience shows that this is true for the large majority of setups.
>  
>  DSI host
> ---------
> +========
>  
>  In addition to the standard properties and those defined by the parent bus of
>  a DSI host, the following properties apply to a node representing a DSI host.
> @@ -30,11 +30,15 @@ Required properties:
>    different value here. See below.
>  
>  DSI peripheral
> ---------------
> +==============
>  
> -Peripherals are represented as child nodes of the DSI host's node. Properties
> -described here apply to all DSI peripherals, but individual bindings may want
> -to define additional, device-specific properties.
> +Peripherals with DSI as control bus
> +------------------------------------
> +
> +Peripherals with the DSI bus as the primary control path are represented as
> +child nodes of the DSI host's node. Properties described here apply to all DSI
> +peripherals, but individual bindings may want to define additional,
> +device-specific properties.

Are there any panels with no control bus? I've never seen one, but it 
should be possible if LVDS panels can power on without commands. 

>  Required properties:
>  - reg: The virtual channel number of a DSI peripheral. Must be in the range
> @@ -49,9 +53,25 @@ case two alternative representations can be chosen:
>    property is the number of the first virtual channel and the second cell is
>    the number of consecutive virtual channels.
>  
> -Example
> --------
> +Peripherals with a different control bus
> +----------------------------------------
> +
> +There are peripherals that have I2C/SPI (or some other non-DSI bus) as the
> +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].
> +
> +[1] Documentation/devicetree/bindings/graph.txt
> +[2] Documentation/devicetree/bindings/media/video-interfaces.txt
>  
> +Examples
> +========
> +- (1), (2) and (3) are examples of a DSI host and peripheral on the DSI bus
> +  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.
> +
> +1)
>  	dsi-host {
>  		...
>  
> @@ -67,6 +87,7 @@ Example
>  		...
>  	};
>  
> +2)
>  	dsi-host {
>  		...
>  
> @@ -82,6 +103,7 @@ Example
>  		...
>  	};
>  
> +3)
>  	dsi-host {
>  		...
>  
> @@ -96,3 +118,42 @@ Example
>  
>  		...
>  	};
> +
> +4)
> +	i2c-host {
> +		...
> +
> +		dsi-bridge@35 {
> +			compatible = "...";
> +			reg = <0x35>;
> +
> +			ports {
> +				#address-cells = <1>;
> +				#size-cells = <0>;
> +
> +				...
> +
> +				port@0 {

Drop unit-address and #*-cells.

> +					bridge_mipi_in: endpoint {
> +						remote-endpoint = <&host_mipi_out>;
> +					};
> +				};
> +			};
> +		};
> +	};
> +
> +	dsi-host {
> +		...
> +
> +		ports {
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +			...
> +
> +			port@0 {

Drop unit-address and #*-cells.

> +				host_mipi_out: endpoint {
> +					remote-endpoint = <&bridge_mipi_in>;
> +				};
> +			};
> +		};
> +	};
> -- 
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