Comment # 6 on bug 1177707 from Takashi Iwai

(In reply to Fabian Vogt from comment #5)
> Is this maybe the same as bug 1177428?

Very likely.  Please try the procedure described in
  https://apibugzilla.suse.com/show_bug.cgi?id=1177428#c58

This should recover the amdgpu firmware.