Re: [PATCH RESEND v2 20/32] drm/vkms: Introduce configfs for plane zpos property

Luca Ceresoli
2025-12-19T17:08:38Z

On Wed Oct 29, 2025 at 3:36 PM CET, Louis Chauvet wrote:
> Modern compositor rely on zpos management to offload some processing to
> deticated hardware. In order to test multiple configurations, add zpos
> configuration to configFS.
>
> Introduce multiple attributes to configure zpos:
> - zpos_enabled - Create or not the zpos property. If not created, the zpos
> is undefined.
> - zpos_mutable - If the zpos property is created, allow or not the
> userspace to modify it
> - zpos_initial - Initial value for zpos property. Must be between zpos_min
> and zpos_max
> - zpos_min - Minimal zpos value for this plane. Must be smaller than or
Minimum

> equals to zpos_max
equal

or, more simply:

- zpos_min - Minimal zpos value for this plane. Must be <= zpos_max

> - zpos_max - Maximal zpos value for this plane. Must be greater than or
Maximum

> equals to zpos_min

As above

> --- a/Documentation/gpu/vkms.rst
> +++ b/Documentation/gpu/vkms.rst

> @@ -114,6 +114,13 @@ Planes have 9 configurable attributes:
> To remove a format, use a minus and its fourcc: -XR24
> To add all formats use +*
> To remove all formats, use -*
> +- zpos_enabled: Enable or not the zpos property: 1 enable, 0 disable
> +- zpos_mutable: Create the zpos property as a mutable or imutable property: 1 mutable,
> + 0 disable. No effect if zpos_enabled is not set.

s/disable/immutable/

> +- zpos_initial: Set the initial zpos value. Must be between zpos_min and zpos_max. No
> + effect if zpos_enabled is not set.
> +- zpos_min: Set the minimal zpos value. No effect if zpos_enabled is not set.
minimum

> +- zpos_max: Set the maximal zpos value. No effect if zpos_enabled is not set.
maximum

With those fixed:

Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering