https://bugs.freedesktop.org/show_bug.cgi?id=29026
--- Comment #13 from Alex Deucher agd5f@yahoo.com 2011-02-10 08:50:04 PST --- (In reply to comment #12)
As I already mentioned the garbled screen issue goes away when using xrandr after resume. I personally fixed this for me by executing the following *dirty* quirk-script on resume:
Can you dump your regs before and after calling xrandr? using radeonreg available here (http://cgit.freedesktop.org/~airlied/radeontool/)
(as root after resume): radeonreg regs all > broken.regs (run xrandr) radeonreg regs all > fixed.regs