Re: [Patch v2 3/6] dt-bindings: display/ti: Add plane binding to dispc node

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Benoit,

Thank you for the patch.

On Monday, 26 March 2018 19:21:25 EEST Benoit Parrot wrote:
> Currently all available display pipelines (i.e. plane) and output port
> resources are exposed to user-space. In some cases it is needed to be
> able to restrict which resources are actually visible from user-space.
> Also in cases where a display wider than 2048 pixels is to be supported
> more than one video pipeline is needed. In this case the 2nd hardware
> pipeline needed is not visible to user space applications.
> 
> These video pipeline definitions must be statically defined so that
> the number of visible pipelines does not change from the user-space
> perspective.
> 
> In order to allow this we are adding an optional 'plane' sub-node to
> the generic DISPC node.

I'm sorry but this is really configuration data, it doesn't describe the 
hardware. I don't think these properties belong to DT.

> Signed-off-by: Benoit Parrot <bparrot@ti.com>
> ---
>  .../devicetree/bindings/display/ti/ti,omap-dss.txt | 65 +++++++++++++++++++
>  1 file changed, 65 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/display/ti/ti,omap-dss.txt
> b/Documentation/devicetree/bindings/display/ti/ti,omap-dss.txt index
> 249e588d7865..2dd411cb5a83 100644
> --- a/Documentation/devicetree/bindings/display/ti/ti,omap-dss.txt
> +++ b/Documentation/devicetree/bindings/display/ti/ti,omap-dss.txt
> @@ -28,6 +28,36 @@ Optional properties:
>  - max-memory-bandwidth: Input memory (from main memory to dispc) bandwidth
> limit in bytes per second
> 
> +Optional Subnode:
> +- plane: Child node(s) which defines which video planes are available to
> +	the system. If at least one plane child node is defined then
> +	only planes defined by these nodes will be available to the system.
> +	Plane nodes must be sequential starting with reg = <0> as DT parsing
> +	will stop on the first missing numbered node.
> +	This means if plane #1 is defined but plane #0 is not then it will
> +	be as if none of the plane nodes were defined.
> +
> +	Each plane node contains the following properties:
> +	Required properties:
> +	- reg:       Used to identify the plane
> +	- video-pipelines: One or two HW pipeline number(s).
> +		When 2 numbers are present this indicates a virtual wide
> +		plane composed of two physical planes intended to be used
> +		when the display is larger then the capacity of a
> +		single plane i.e. wider than 2048 pixels.
> +		The first number in the pair will dictate the capabilities
> +		of the plane. This means that for proper
> +		operation the virtual plane should be composed of HW
> +		planes of the same capabilities.
> +		If GFX pipeline is used in a virtual plane it should be
> +		specified first, otherwise unexpected behavior would
> +		be encountered.
> +	Optional property:
> +	- video-outputs:  One or more HW output number(s).
> +		Describe the list of video output on which this plane
> +		is available. If this node is not present then the
> +		plane will be available on all available video output.
> +
>  Video Ports
>  -----------
> 
> @@ -216,3 +246,38 @@ OMAP HDMI --(HDMI)--> TPD12S015 --(HDMI)--> HDMI
> Connector };
>  	};
>  };
> +
> +A short example on how to define a virtual plane configuration
> +to enable wide display support.
> +Here we define:
> +- plane#0 to be the HW pipeline #0 (i.e. GFX pipeline)
> +	  only available on video output #0
> +- plane#1 to be a virtual wide plane composed of HW pipeline #1 and #2
> +	  (i.e. VID1 & VID2) available on video output #0 & #1
> +- plane#2 to be the HW pipeline #3 (i.e. VID3 pipeline)
> +	  only available on video output #0
> +
> +&dss {
> +        dispc@58001000 {
> +                #address-cells = <1>;
> +                #size-cells = <0>;
> +
> +                plane@0 {
> +                        reg = <0>;
> +                        video-pipelines = <0>;
> +                        video-outputs = <0>;
> +                };
> +
> +                plane@1 {
> +                        reg = <1>;
> +                        video-pipelines = <1 2>;
> +                        video-outputs = <0 1>;
> +                };
> +
> +                plane@2 {
> +                        reg = <2>;
> +                        video-pipelines = <3>;
> +                        video-outputs = <0>;
> +                };
> +        };
> +};


-- 
Regards,

Laurent Pinchart



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