On 8/28/26 6:02 AM, [email protected] wrote: > From: Shixiong Ou <[email protected]> > > The vkms planes expose formats with an alpha channel but do not > create the pixel blend mode property. Since > commit 860e748bddcc ("drm: ensure blend mode supported if pixel > format with alpha exposed") this triggers a warning during > drm_mode_config_validate(): > > [ 993.538979] ------------[ cut here ]------------ > [ 993.539000] [PLANE:35:plane-0] pixel format with alpha exposed but blend > mode not setup > [ 993.539063] WARNING: drivers/gpu/drm/drm_mode_config.c:872 at > drm_mode_config_validate > ...... > [ 993.539578] Call trace: > [ 993.539580] drm_mode_config_validate+0x398/0x558 [drm] (P) > [ 993.539707] drm_dev_register+0x1cc/0x2a0 [drm] > [ 993.539832] vkms_create+0x184/0x1d0 [vkms] > [ 993.539854] vkms_init+0x78/0xff8 [vkms] > ...... > > The vkms composer only blends premultiplied alpha, see > pre_mul_alpha_blend(), so create the property with > DRM_MODE_BLEND_PREMULTI as the only supported mode. > > Reported-by: Ye Liu <[email protected]> > Signed-off-by: Shixiong Ou <[email protected]> > --- > drivers/gpu/drm/vkms/vkms_plane.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/drivers/gpu/drm/vkms/vkms_plane.c > b/drivers/gpu/drm/vkms/vkms_plane.c > index 6ee5c3f3207c..c4272f5f0354 100644 > --- a/drivers/gpu/drm/vkms/vkms_plane.c > +++ b/drivers/gpu/drm/vkms/vkms_plane.c > @@ -276,6 +276,7 @@ struct vkms_plane *vkms_plane_init(struct vkms_device > *vkmsdev, > { > struct drm_device *dev = &vkmsdev->drm; > struct vkms_plane *plane; > + int ret; > > plane = drmm_universal_plane_alloc(dev, struct vkms_plane, base, 0, > &vkms_plane_funcs, > @@ -287,6 +288,15 @@ struct vkms_plane *vkms_plane_init(struct vkms_device > *vkmsdev, > > drm_plane_helper_add(&plane->base, &vkms_plane_helper_funcs); > > + /* > + * The vkms composer only blends premultiplied alpha, see > + * pre_mul_alpha_blend(), so that is the only supported mode. > + */ > + ret = drm_plane_create_blend_mode_property(&plane->base, > + > BIT(DRM_MODE_BLEND_PREMULTI)); > + if (ret) > + return ERR_PTR(ret); > + Hello, This looks good to me! But I think the comment in pre_mul_alpha_blend() could also be updated. It states: "The current DRM assumption is that pixel color values have been already pre-multiplied with the alpha channel values" Which is not true anymore. With this change: Reviewed-by: Leandro Ribeiro <[email protected]> > drm_plane_create_rotation_property(&plane->base, DRM_MODE_ROTATE_0, > DRM_MODE_ROTATE_MASK | > DRM_MODE_REFLECT_MASK); > -- Leandro Ribeiro
