(In reply to Michael de Lang from comment #156)
> Just had a hang using 5.4.0-rc3, mesa 19.3~git1910171930.4b458b~oibaf~d,
> AMD_DEBUG="nodma nongg" while using firefox:
> 
> Oct 24 16:31:26 oipo-X570-AORUS-ELITE kernel: [27386.467009] broken atomic
> modeset userspace detected, disabling atomic
> Oct 24 21:04:58 oipo-X570-AORUS-ELITE kernel: [43796.470041]
> [drm:amdgpu_dm_atomic_commit_tail [amdgpu]] *ERROR* Waiting for fences timed
> out!
> Oct 24 21:04:58 oipo-X570-AORUS-ELITE kernel: [43798.773602]
> [drm:amdgpu_job_timedout [amdgpu]] *ERROR* ring sdma0 timeout, signaled
> seq=1756792, emitted seq=1756794
> Oct 24 21:04:58 oipo-X570-AORUS-ELITE kernel: [43798.773683]
> [drm:amdgpu_job_timedout [amdgpu]] *ERROR* Process information: process GPU
> Process pid 17048 thread firefox:cs0 pid 17134
> Oct 24 21:04:58 oipo-X570-AORUS-ELITE kernel: [43798.773685] [drm] GPU
> recovery disabled.

Ok this doesn't sound right, how can you get an SDMA hang if you disable DMA
completely. command should be:
AMD_DEBUG=nodma
not
AMD_DEBUG="nodma"