(In reply to comment #4)
> Can you bisect?

The result of the bisection:

~/src/linux-git> git bisect good
d4788db30a1a66255b592dd12613dda80c1443f7 is the first bad commit
commit d4788db30a1a66255b592dd12613dda80c1443f7
Author: Alex Deucher <alexander.deucher@amd.com>
Date:   Thu Feb 28 14:40:09 2013 -0500

    drm/radeon/evergreen: add support for golden register init

    Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

:040000 040000 b95956fea3e6171d7cf631a812a76541e76835cf
f352e1babbc86bf91f9693eb1c903e5f5c947c22 M      drivers