Using the soon-to-be linux 5.4.0-rc1 (574cc4539762561d96b456dbc0544d8898bd4c6e) with oibaf's ppa for DRI, I get the following messages in my kernel.log:
Sep 20 18:12:19 oipo-X570-AORUS-ELITE kernel: [23162.876229] [drm:amdgpu_job_timedout [amdgpu]] *ERROR* ring sdma1 timeout, signaled seq=140067, emitted seq=140070
Sep 20 18:12:19 oipo-X570-AORUS-ELITE kernel: [23162.876310] [drm:amdgpu_job_timedout [amdgpu]] *ERROR* Process information: process GPU Process pid 16418 thread firefox:cs0 pid 16498
Sep 20 18:12:19 oipo-X570-AORUS-ELITE kernel: [23162.876312] [drm] GPU recovery disabled.
Music stops playing, desktop becomes completely unresponsive except for mouse. Mouse can be moved normally.
Hardware: Radeon RX 5700
See also https://bugs.freedesktop.org/show_bug.cgi?id=111481 were similar issues were reported.
For now, it seems that the only reliable workaround is to use the Mesa environment variable "AMD_DEBUG=nodma".
Much appreciated, will test that and if it seems to help, then this can be closed as duplicate.
Confirmed workaround from #111481 to fix freezes.
*** This bug has been marked as a duplicate of bug 111481 ***