interestingly also the last good commit produces the following log:
[    7.573975] [drm] UVD initialized successfully.
[    7.574210] [drm] Enabling audio 0 support
[    7.574240] [drm] ib test on ring 0 succeeded in 0 usecs
[    7.574263] [drm] ib test on ring 3 succeeded in 0 usecs
[   17.730386] radeon 0000:01:00.0: GPU lockup CP stall for more than 10000msec
[   17.730390] radeon 0000:01:00.0: GPU lockup (waiting for 0x0000000000000002
last fence id 0x0000000000000000)
[   17.730393] [drm:uvd_v1_0_ib_test] *ERROR* radeon: fence wait failed (-35).
[   17.730397] [drm:radeon_ib_ring_tests] *ERROR* radeon: failed testing IB on
ring 5 (-35).

So that seems unrelated to the issue at hand.