(In reply to Sandeep from comment #10)
> I tried the 4.11.0 kernel since I suspected that the buggy change might also
> be present in the point releases, but that also caused a hang whenplaying
> Left 4 Dead 2. Will try older kernels and see if they work correctly (which
> they should since this hang definitely wasn't present 2 months ago).

Yep, Sandeep, I think this behaviour is tied to DPM issues highlighted in Bug
91880 : 'Radeonsi on Grenada cards (r9 390) exceptionally unstable and poorly
performing'. I suggest following, reading, and commenting on that issue.