https://bugs.freedesktop.org/show_bug.cgi?id=42490
--- Comment #22 from Alex Deucher agd5f@yahoo.com 2012-04-29 05:27:18 PDT --- (In reply to comment #19)
Created attachment 60758 [details] dmesg with proposed patch and drm.debug=4
Mine is and the patch doesn't correct the problem.
Does it work if you boot without VGA attached and then enable it later? How about if you disable VGA with xrandr and then re-enable it? E.g.: xrandr --output VGA-0 --off xrandr --output VGA-0 --auto