(In reply to Andy Furniss from comment #14)
> (In reply to Mathias Tillman from comment #13)
> > Created attachment 117871 [details] [review] [review] [review]
> > Potential fix
> > 
> > Andy: Could you test the attached patch, please? It's now working fine for
> > me.
> 
> It also seems to be working for me :-)

It gets better - there is a chance that this (well it + working current libdrm
it enables) has fixed a long standing UVD issue and a more recent vapau_interop
one (basically both would randomly fail). It's slightly possible that something
else fixed it - will have to play over coming days.