On 2/14/19 11:47 AM, Grodzovsky, Andrey wrote: > > On 2/14/19 11:07 AM, Michel Dänzer wrote: >> On 2019-02-14 4:54 p.m., Kazlauskas, Nicholas wrote: >>> On 2/14/19 10:42 AM, Grodzovsky, Andrey wrote: >>>> On 2/14/19 4:05 AM, Christian König wrote: >>>>> Am 13.02.19 um 19:58 schrieb Andrey Grodzovsky: >>>>>> When ring hang happens amdgpu_dm_commit_planes during flip is holding >>>>>> the BO reserved and then stack waiting for fences to signal in >>>>>> reservation_object_wait_timeout_rcu (which won't signal because there >>>>>> was a hnag). Then when we try to shutdown display block during reset >>>>>> recovery from drm_atomic_helper_suspend we also try to reserve the BO >>>>>> from dm_plane_helper_cleanup_fb ending in deadlock. >>>>>> Also remove useless WARN_ON >>>>> Well it is good that you pointed this out, but there are more problems >>>>> than just waiting wile the BO is reserved here. >>>>> >>>>>> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@xxxxxxx> >>>>>> --- >>>>>> drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 19 >>>>>> +++++++++++++------ >>>>>> 1 file changed, 13 insertions(+), 6 deletions(-) >>>>>> >>>>>> 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 acc4ff8..f8dec36 100644 >>>>>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c >>>>>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c >>>>>> @@ -4802,14 +4802,21 @@ static void amdgpu_dm_commit_planes(struct >>>>>> drm_atomic_state *state, >>>>>> */ >>>>>> abo = gem_to_amdgpu_bo(fb->obj[0]); >>>>>> r = amdgpu_bo_reserve(abo, true); >>>>> Well why do we reserve the BO in the first place? As the name >>>>> indicates reservation_object_wait_timeout_rcu() just uses rcu to wait >>>>> for the BO to be idle, no need to actually reserve it at all. >>>> That a good point, I honestly can't remember any more why it's here... >>>> It does look unnecessary given that we are not validating the BO here. >>> I think we reserve it to grab the tiling flags to update the plane >>> address (and some other bits of the plane state with a patch I'm >>> currently working on). I'm guessing that we still need the reservation >>> so nothing else tries to grab it after it becomes idle, but I'm not >>> overly familiar with that bit. >> The BO is already pinned at this point, isn't it? That's enough to >> prevent it from moving, no reservation needed. > > > Yes, agree. > > Andrey > > >> >> I'm not worried about the buffer moving so much as I am about userspace changing the tiling flags by calling the IOCTL. Can that happen when it's pinned? Nicholas Kazlauskas _______________________________________________ amd-gfx mailing list amd-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/amd-gfx
