[PATCH] drm: rcar-du: Create immutable zpos property for primary planes

[Geert Uytterhoeven]

Hi Laurent,

On Thu, Apr 2, 2020 at 12:42 PM Laurent Pinchart
<laurent.pinchart+renesas at ideasonboard.com> wrote:
> The R-Car DU driver creates a zpos property, ranging from 1 to 7, for
> all the overlay planes, but leaves the primary plane without a zpos
> property. The DRM/KMS API doesn't clearly specify if this is acceptable,
> of it the property is mandatory for all planes when exposed for some of
> the planes. Nonetheless, weston v8.0 has been reported to have trouble
> handling this situation.
>
> The DRM core offers support for immutable zpos properties. Creating an
> immutable zpos property set to 0 for the primary planes seems to be a
> good way forward, as it shouldn't introduce any regression, and can fix
> the issue. Do so.
>
> Reported-by: Kuninori Morimoto <kuninori.morimoto.gx at renesas.com>
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas at ideasonboard.com>

Thanks for your patch!

> --- a/drivers/gpu/drm/rcar-du/rcar_du_plane.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_plane.c
> @@ -785,13 +785,15 @@ int rcar_du_planes_init(struct rcar_du_group *rgrp)
>
>                 drm_plane_create_alpha_property(&plane->plane);
>
> -               if (type == DRM_PLANE_TYPE_PRIMARY)
> -                       continue;
> -
> -               drm_object_attach_property(&plane->plane.base,
> -                                          rcdu->props.colorkey,
> -                                          RCAR_DU_COLORKEY_NONE);
> -               drm_plane_create_zpos_property(&plane->plane, 1, 1, 7);
> +               if (type == DRM_PLANE_TYPE_PRIMARY) {
> +                       drm_plane_create_zpos_immutable_property(&plane->plane,
> +                                                                0);
> +               } else {
> +                       drm_object_attach_property(&plane->plane.base,
> +                                                  rcdu->props.colorkey,
> +                                                  RCAR_DU_COLORKEY_NONE);
> +                       drm_plane_create_zpos_property(&plane->plane, 1, 1, 7);
> +               }
>         }
>
>         return 0;

This is very similar to Esaki-san's patch[*] posted yesterday.
However, there's one big difference: your patch doesn't update
rcar_du_vsp_init(). Isn't that needed?

[*] "[PATCH] drm: rcar-du: Set primary plane zpos immutably at initializing"
    https://lore.kernel.org/linux-renesas-soc/20200401061100.7379-1-etom@igel.co.jp/

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds