https://bugs.freedesktop.org/show_bug.cgi?id=91790
--- Comment #4 from Andy Furniss adf.lists@gmail.com --- (In reply to Christian König from comment #3)
That could just be a symptom of a hardware hang which isn't detected for some reason.
There's this - drm/amdgpu: disable GPU reset by default
http://cgit.freedesktop.org/~agd5f/linux/commit/?h=drm-next-4.3&id=a895c...