On Wed, Mar 13, 2019 at 8:21 PM Helen Koike <helen.koike@xxxxxxxxxxxxx> wrote: > > Async update callbacks are expected to set the old_fb in the new_state > so prepare/cleanup framebuffers are balanced. > > Cc: <stable@xxxxxxxxxxxxxxx> # v4.14+ > Fixes: 224a4c970987 ("drm/msm: update cursors asynchronously through atomic") > Suggested-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx> > Signed-off-by: Helen Koike <helen.koike@xxxxxxxxxxxxx> > > --- > Hello, > > As mentioned in the cover letter, > But I couldn't test on MSM because I don't have the hardware and I would > appreciate if anyone could test it. > > In other platforms (VC4, AMD, Rockchip), there is a hidden > drm_framebuffer_get(new_fb)/drm_framebuffer_put(old_fb) in async_update > that is wrong, but I couldn't identify those here, not sure if it is hidden > somewhere else, but if tests fail this is probably the cause. > > Thanks! > Helen Apologies, I haven't had a chance to test this yet, and it is likely to be a few weeks before I have a chance.. That said, not refcnt'ing the fb seems suspicious. I read the explanation in the other patches, but kind of think it is more clear to keep the extra refcnt'ing.. or at least have a comment. I do a bit wonder if we hold the ref to the outgoing cursor long enough.. I think the hw will actually continue to scan it out until the next vblank. But Archit was the one who added async_update support so maybe that is handled somewhere else. It's been a while since I've looked at this. BR, -R > > Changes in v3: None > Changes in v2: > - update CC stable and Fixes tag > > drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c b/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c > index be13140967b4..b854f471e9e5 100644 > --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c > +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c > @@ -502,6 +502,8 @@ static int mdp5_plane_atomic_async_check(struct drm_plane *plane, > static void mdp5_plane_atomic_async_update(struct drm_plane *plane, > struct drm_plane_state *new_state) > { > + struct drm_framebuffer *old_fb = plane->state->fb; > + > plane->state->src_x = new_state->src_x; > plane->state->src_y = new_state->src_y; > plane->state->crtc_x = new_state->crtc_x; > @@ -524,6 +526,8 @@ static void mdp5_plane_atomic_async_update(struct drm_plane *plane, > > *to_mdp5_plane_state(plane->state) = > *to_mdp5_plane_state(new_state); > + > + new_state->fb = old_fb; > } > > static const struct drm_plane_helper_funcs mdp5_plane_helper_funcs = { > -- > 2.20.1 >