Op 09-06-17 om 23:30 schreef Andrey Grodzovsky: > Problem: > While running IGT kms_atomic_transition test suite i encountered > a hang in drmHandleEvent immidietly follwoing an atomic_commit. > After dumping the atomic state I relized that in this case there was > not even one CRTC attached to the state and only disabled > planes. This probably due to a commit which hadn't changed any property > which would require attaching crtc state. This means drmHandleEvent > will never wake up from read since without CRTC in atomic state > the event fd will not be singnaled. > This point to a bug in IGT but also DRM should gracefully > fail such scenario so no hang on user side will happen. > > Fix: > Explicitly fail by failing atomic_commit early in > drm_mode_atomic_commit where such problem can be identified. > > Signed-off-by: Andrey Grodzovsky <Andrey.Grodzovsky at amd.com> > --- > drivers/gpu/drm/drm_atomic.c | 13 ++++++++++++- > 1 file changed, 12 insertions(+), 1 deletion(-) Patch itself looks sane, but I'm worried about failing with -EINVAL when the same configuration with TEST_ONLY would otherwise succeed on it. Not sure whether we should fail or not, since sending 0 events could still be considered success. I don't mind either way, but definitely something that should be discussed before applying.
