> -----Original Message----- > From: Borah, Chaitanya Kumar <[email protected]> > Sent: Wednesday, July 15, 2026 11:12 AM > To: [email protected]; [email protected] > Cc: Borah, Chaitanya Kumar <[email protected]>; Ville Syrjälä > <[email protected]>; Shankar, Uma <[email protected]>; > Leandro Ribeiro <[email protected]> > Subject: [PATCH] drm/i915/display: expose blend mode on alpha-capable planes > > Since commit 860e748bddcc ("drm: ensure blend mode supported if pixel format > with alpha exposed"), drm_mode_config_validate() warns when a plane exposes > an alpha pixel format but not the "pixel blend mode" > property. The cursor (ARGB8888, all platforms) and the VLV/CHV primary and > sprite planes trip this. > > Userspace has historically assumed premultiplied blending when the property is > not attached, so it is safe to assume that planes that did not expose the > property > already blended with fixed pre-multiplied alpha in hardware. Therefore, > expose a > "pixel blend mode" property advertising only DRM_MODE_BLEND_PREMULTI to > match that assumption and silence the warning. The cursor call is > unconditional; > the primary and sprite calls are gated to VLV/CHV, the only platforms whose > format lists include alpha formats.
Looks Good to me. Reviewed-by: Uma Shankar <[email protected]> > Assisted-by: Claude:claude-opus-4-8 > Cc: Ville Syrjälä <[email protected]> > Cc: Uma Shankar <[email protected]> > Cc: Leandro Ribeiro <[email protected]> > Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/work_items/16623 > Signed-off-by: Chaitanya Kumar Borah <[email protected]> > --- > drivers/gpu/drm/i915/display/i9xx_plane.c | 4 ++++ > drivers/gpu/drm/i915/display/intel_cursor.c | 3 +++ > drivers/gpu/drm/i915/display/intel_sprite.c | 4 ++++ > 3 files changed, 11 insertions(+) > > diff --git a/drivers/gpu/drm/i915/display/i9xx_plane.c > b/drivers/gpu/drm/i915/display/i9xx_plane.c > index 70734d32a409..490908f59141 100644 > --- a/drivers/gpu/drm/i915/display/i9xx_plane.c > +++ b/drivers/gpu/drm/i915/display/i9xx_plane.c > @@ -1108,6 +1108,10 @@ intel_primary_plane_create(struct intel_display > *display, enum pipe pipe) > DRM_MODE_ROTATE_0, > supported_rotations); > > + if (display->platform.valleyview || display->platform.cherryview) > + drm_plane_create_blend_mode_property(&plane->base, > + > BIT(DRM_MODE_BLEND_PREMULTI)); > + > zpos = 0; > drm_plane_create_zpos_immutable_property(&plane->base, zpos); > > diff --git a/drivers/gpu/drm/i915/display/intel_cursor.c > b/drivers/gpu/drm/i915/display/intel_cursor.c > index 88384dea868b..0673f16f6fd0 100644 > --- a/drivers/gpu/drm/i915/display/intel_cursor.c > +++ b/drivers/gpu/drm/i915/display/intel_cursor.c > @@ -1078,6 +1078,9 @@ intel_cursor_plane_create(struct intel_display *display, > > intel_cursor_add_size_hints_property(cursor); > > + drm_plane_create_blend_mode_property(&cursor->base, > + > BIT(DRM_MODE_BLEND_PREMULTI)); > + > zpos = DISPLAY_RUNTIME_INFO(display)->num_sprites[pipe] + 1; > drm_plane_create_zpos_immutable_property(&cursor->base, zpos); > > diff --git a/drivers/gpu/drm/i915/display/intel_sprite.c > b/drivers/gpu/drm/i915/display/intel_sprite.c > index 6a65f92e8a03..3e38960bbbd8 100644 > --- a/drivers/gpu/drm/i915/display/intel_sprite.c > +++ b/drivers/gpu/drm/i915/display/intel_sprite.c > @@ -1722,6 +1722,10 @@ intel_sprite_plane_create(struct intel_display > *display, > DRM_COLOR_YCBCR_BT709, > > DRM_COLOR_YCBCR_LIMITED_RANGE); > > + if (display->platform.valleyview || display->platform.cherryview) > + drm_plane_create_blend_mode_property(&plane->base, > + > BIT(DRM_MODE_BLEND_PREMULTI)); > + > zpos = sprite + 1; > drm_plane_create_zpos_immutable_property(&plane->base, zpos); > > -- > 2.25.1
