(In reply to nmr from comment #26)
> I'm getting the impression that AMD does not regard the kernel hang as the
> underlying issue. Is that correct?

The GPU hang is most likely caused by a bug in mesa.  What kernel are you
using?  GPU reset was only recently enabled by default on certain asics.  Even
if a GPU reset is successful, user mode programs (like X or the wayland desktop
compositor) need to properly catch and handle GPU resets which they don't
currently today.  Can you try 4.20 or newer?