On Mon, Mar 16, 2026 at 03:55:07PM -0700, Austin Hu wrote: > Some libdrm user mode apps (including compositor) disable unused > plane with its previously binded CRTC or frame buffer object, but > may not reset its properties like src/dst coordinates, so that some > values of the unused plane state would be sticky. And even with > some Display Engine IP like Intel, a plane disabled from user mode > in current frame may be linked with another plane (e.g. to DMA Y or > UV semi-planar buffer) in KMD driver, so that its sticky UAPI > settings mismatch with the ones programmed to registers. > > So clear the unused plane state during each atomic commit, to make > sure each plane state is up to date. This change might be > unnecessary if user mode already clears plane property, but keep it > just in case.
The kernel isn't allowed to magically change the value of properties set by userspace, apart from a few special cases. No idea what you're actually trying to fix here, but sounds like your userspace might be broken and needs to be fixed. > > Signed-off-by: Austin Hu <[email protected]> > --- > drivers/gpu/drm/drm_atomic.c | 62 ++++++++++++++++++++++++++++++++++-- > 1 file changed, 59 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c > index dd9f27cfe991..0ce57e540a86 100644 > --- a/drivers/gpu/drm/drm_atomic.c > +++ b/drivers/gpu/drm/drm_atomic.c > @@ -690,6 +690,59 @@ plane_switching_crtc(const struct drm_plane_state > *old_plane_state, > return true; > } > > +/** > + * drm_atomic_plane_state_reset - reset plane state > + * @plane: plane to reset > + * @plane_state: plane state to reset > + * > + * This function resets the plane state to its default values, after > + * the plane is disabled or when the plane state is no longer valid. > + */ > +static int drm_atomic_plane_state_reset(struct drm_plane *plane, > + struct drm_plane_state *plane_state) > +{ > + int ret; > + > + ret = drm_atomic_set_crtc_for_plane(plane_state, NULL); > + if (ret != 0) > + return ret; > + > + drm_atomic_set_fb_for_plane(plane_state, NULL); > + > + plane_state->crtc_x = 0; > + plane_state->crtc_y = 0; > + plane_state->crtc_w = 0; > + plane_state->crtc_h = 0; > + plane_state->src_x = 0; > + plane_state->src_y = 0; > + plane_state->src_w = 0; > + plane_state->src_h = 0; > + > + plane_state->alpha = 0; > + plane_state->pixel_blend_mode = 0; > + plane_state->rotation = 0; > + plane_state->zpos = 0; > + plane_state->color_encoding = 0; > + plane_state->color_range = 0; > + > + drm_atomic_set_colorop_for_plane(plane_state, NULL); > + > + bool replaced = false; > + > + ret = drm_property_replace_blob_from_id( > + plane->dev, &plane_state->fb_damage_clips, 0, -1, -1, > + sizeof(struct drm_mode_rect), &replaced); > + if (ret) > + return ret; > + > + plane_state->scaling_filter = 0; > + plane_state->hotspot_x = 0; > + plane_state->hotspot_y = 0; > + plane_state->visible = false; > + > + return 0; > +} > + > /** > * drm_atomic_plane_check - check plane state > * @old_plane_state: old plane state to check > @@ -701,7 +754,7 @@ plane_switching_crtc(const struct drm_plane_state > *old_plane_state, > * Zero on success, error code on failure > */ > static int drm_atomic_plane_check(const struct drm_plane_state > *old_plane_state, > - const struct drm_plane_state *new_plane_state) > + struct drm_plane_state *new_plane_state) > { > struct drm_plane *plane = new_plane_state->plane; > struct drm_crtc *crtc = new_plane_state->crtc; > @@ -721,9 +774,12 @@ static int drm_atomic_plane_check(const struct > drm_plane_state *old_plane_state, > return -EINVAL; > } > > - /* if disabled, we don't care about the rest of the state: */ > + /* > + * if disabled, we don't care about the rest of the state: > + * but clear the plane state. > + */ > if (!crtc) > - return 0; > + return drm_atomic_plane_state_reset(plane, new_plane_state); > > /* Check whether this plane is usable on this CRTC */ > if (!(plane->possible_crtcs & drm_crtc_mask(crtc))) { > -- > 2.34.1 -- Ville Syrjälä Intel
