[PATCH] drm/amd/display: Fix overlay validation by considering cursors

[Mark Yacoub]

On Fri, May 14, 2021 at 11:28 AM Harry Wentland <harry.wentland at amd.com> wrote:
>
> On 2021-05-14 7:47 a.m., Rodrigo Siqueira wrote:
> > A few weeks ago, we saw a two cursor issue in a ChromeOS system. We
> > fixed it in the commit:
> >
> >  drm/amd/display: Fix two cursor duplication when using overlay
> >  (read the commit message for more details)
> >
> > After this change, we noticed that some IGT subtests related to
> > kms_plane and kms_plane_scaling started to fail. After investigating
> > this issue, we noticed that all subtests that fail have a primary plane
> > covering the overlay plane, which is currently rejected by amdgpu dm.
> > Fail those IGT tests highlight that our verification was too broad and
> > compromises the overlay usage in our drive. This patch fixes this issue
> > by ensuring that we only reject commits where the primary plane is not
> > fully covered by the overlay when the cursor hardware is enabled. With
> > this fix, all IGT tests start to pass again, which means our overlay
> > support works as expected.
> >
> > Cc: Tianci.Yin <tianci.yin at amd.com>
> > Cc: Harry Wentland <harry.wentland at amd.com>
> > Cc: Nicholas Choi <nicholas.choi at amd.com>
> > Cc: Bhawanpreet Lakha <bhawanpreet.lakha at amd.com>
> > Cc: Nicholas Kazlauskas <Nicholas.Kazlauskas at amd.com>
> > Cc: Mark Yacoub <markyacoub at google.com>
> > Cc: Daniel Wheeler <daniel.wheeler at amd.com>
> >
> > Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira at amd.com>
> > ---
> >  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 +++++++++-
> >  1 file changed, 9 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > index ccd67003b120..9c2537a17a7b 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > @@ -10067,7 +10067,7 @@ static int validate_overlay(struct drm_atomic_state *state)
> >       int i;
> >       struct drm_plane *plane;
> >       struct drm_plane_state *old_plane_state, *new_plane_state;
> > -     struct drm_plane_state *primary_state, *overlay_state = NULL;
> > +     struct drm_plane_state *primary_state, *cursor_state, *overlay_state = NULL;
> >
> >       /* Check if primary plane is contained inside overlay */
> >       for_each_oldnew_plane_in_state_reverse(state, plane, old_plane_state, new_plane_state, i) {
> > @@ -10097,6 +10097,14 @@ static int validate_overlay(struct drm_atomic_state *state)
> >       if (!primary_state->crtc)
> >               return 0;
> >
> > +     /* check if cursor plane is enabled */
> > +     cursor_state = drm_atomic_get_plane_state(state, overlay_state->crtc->cursor);
> > +     if (IS_ERR(cursor_state))
> > +             return PTR_ERR(cursor_state);
> > +
> > +     if (drm_atomic_plane_disabling(plane->state, cursor_state))
> > +             return 0;
> > +
>
> I thought this breaks Chrome's compositor since it can't handle an atomic commit rejection
> based solely on whether a cursor is enabled or not.
>
> Harry
>
> >       /* Perform the bounds check to ensure the overlay plane covers the primary */
> >       if (primary_state->crtc_x < overlay_state->crtc_x ||
> >           primary_state->crtc_y < overlay_state->crtc_y ||
> >
>