(In reply to comment #7)
> (In reply to comment #4)
> > Is this a regression?  Was dpm working previously at some point, if so when?
> 
> It worked fine in 3.11 and 3.12. The problem appeared somewhere during the
> development of 3.13. At those point vgaswitcheroo didn't work and I had to
> stick to older versions of the kernel.

Any chance you could bisect?