(In reply to Michel Dänzer from comment #8)
> (In reply to Rafael Ristovski from comment #7)
> > I just downgraded, PRIME worked flawlessly up until 3.19, I was able to test
> > up until 3.17.6-1 since the next one after that was the latest kernel in the
> > [testing] repo aka 3.19.2-1
> 
> Can you narrow it down further, ideally bisect?

I guess I could try, but not in the near future as I lack free time. Will
report back once done or when any progress is made.