[Patch 2/4] dt-bindings: display/ti: Add plane binding to dispc node

[Rob Herring]

On Fri, Mar 2, 2018 at 7:48 AM, Benoit Parrot <bparrot at ti.com> wrote:
> Add 'plane' child node to generic DISPC node as an optional
> property.

Why? What problem are you solving?

>
> Signed-off-by: Benoit Parrot <bparrot at ti.com>
> ---
>  .../devicetree/bindings/display/ti/ti,omap-dss.txt | 63 ++++++++++++++++++++++
>  1 file changed, 63 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..cb101525b805 100644
> --- a/Documentation/devicetree/bindings/display/ti/ti,omap-dss.txt
> +++ b/Documentation/devicetree/bindings/display/ti/ti,omap-dss.txt
> @@ -27,6 +27,34 @@ DISPC
>  Optional properties:
>  - max-memory-bandwidth: Input memory (from main memory to dispc) bandwidth limit
>                         in bytes per second
> +- plane: Child node(s) which defines which logical plane are available to

This is the "Optional properties" section and plane is not a property.

> +       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 number the logical plane

Is logical plane a h/w concept?

> +       - hw-planes: One or two HW plane number(s).
> +                    When 2 numbers are present this indicates a virtual 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 virtual plane. This means that for proper
> +                    operation the virtual plane should be composed of HW
> +                    planes of the same capabilities.
> +                    If GFX plane is used in a virtual plane it should be
> +                    specified first, otherwise unexpected behavior would
> +                    be encountered.
> +       Optional property:
> +       - hw-crtcs:  One or more HW crtc number(s).
> +                    Describe the list of CRTCs on which this plane is
> +                    available. If this node is not present then the
> +                    plane will be available on all available CRTCs.

Let's not copy archaic terms from DRM into bindings.

Really, I'm skeptical that any of this belongs in DT. For example,
can't you figure out you need 2 physical planes whenever your
panel/timing width is greater than 2048?

Rob