https://bugs.freedesktop.org/show_bug.cgi?id=49747
--- Comment #9 from Daniel Vetter daniel@ffwll.ch 2012-05-10 13:14:35 PDT --- I've forgot to add, after some extensive playing around I see:
[ 116.394377] [drm:radeon_dp_get_link_status] *ERROR* displayport link status failed [ 143.302728] [drm:radeon_dp_get_link_status] *ERROR* displayport link status failed
in dmesg. I'll try the other stuff right away.