I'm using kernel 3.13-rc0 from:
http://kernel.ubuntu.com/~kernel-ppa/mainline/drm-next/2013-11-14-trusty/
3.12.0-996-generic #201311140516
and this is still happening...
I guess I'll have to go back to fglrx.
I wished I could help devs, but this is driving me crazy. Not being able to
resume from suspend is why I wanted to test the open-source driver in the first
place...