A patch referencing this bug report has been merged in Linux v3.8-rc5:

commit 20707874fd4fd37e09513f508e642fa8bd06365a
Author: Alex Deucher <alexander.deucher@amd.com>
Date:   Thu Jan 17 13:10:50 2013 -0500

    Revert "drm/radeon: do not move bo to different placement at each cs"