Re: warnings from validate_blend_mode_for_alpha_formats() in next-20260715

[Alex Deucher]

+ Some display folks

On Fri, Jul 17, 2026 at 9:04 AM Bert Karwatzki <spasswolf@xxxxxx> wrote:
>
> commit 860e748bddcc ("drm: ensure blend mode supported if pixel format with alpha exposed")
> introduces validate_blend_mode_for_alpha_formats() which prints warnings for amdpgu as
> amdgpu only set blend_mode_property for planes of type DRM_PLANE_TYPE_OVERLAY. I tried to fix
> this by removing he (plane->type == DRM_PLANE_TYPE_OVERLAY) check in amdgpu_dm_plane_init():
>
>         printk(KERN_INFO "%s: plane=%px plane->type=0x%x plane_cap=%px\n", __func__, plane, plane->type, plane_cap);
>         if (plane_cap)
>                 printk(KERN_INFO "%s: per_pixel_alpha =%u\n", __func__, plane_cap->per_pixel_alpha);
>         if (plane_cap && plane_cap->per_pixel_alpha) {
>                 unsigned int blend_caps = BIT(DRM_MODE_BLEND_PIXEL_NONE) |
>                                           BIT(DRM_MODE_BLEND_PREMULTI) |
>                                           BIT(DRM_MODE_BLEND_COVERAGE);
>
>                 printk(KERN_INFO "%s: creating alpha and blend mode properties for plane %px\n", __func__, plane);
>                 drm_plane_create_alpha_property(plane);
>                 drm_plane_create_blend_mode_property(plane, blend_caps);
>         }
>
> But this does not completely silence the warnings becuase for planes of type DRM_PLANE_TYPE_CURSOR plane_cap is NULL.
> Is this a problem that should be fixed in amdgpu or is should validate_blend_mode_for_alpha_formats() only be called
> for planes of certain types?
>
> Bert Karwatzki
>