https://bugs.freedesktop.org/show_bug.cgi?id=39714
--- Comment #4 from Michel Dänzer michel@daenzer.net 2011-08-31 06:43:22 PDT --- (In reply to comment #3)
Here's my theory on what's happening:
Another possibility might be that e.g. PAT / MTRR attributes aren't properly restored for some memory areas. Can you attach the following files from before/after suspend/resume:
/sys/kernel/debug/dri/0/radeon_*_mm /sys/kernel/debug/x86/pat_memtype_list /proc/mtrr