https://bugs.freedesktop.org/show_bug.cgi?id=79980
--- Comment #185 from Michel Dänzer michel@daenzer.net --- (In reply to agapito from comment #184)
Can you bisect which commit in 3.18-rc2 fixed it for you?
Sorry, I do not know how to do it.
Search the web for 'git bisect howto'. One gotcha is that you'll need to run 'git bisect good' for bad kernels and vice versa, because git bisect can only isolate good -> bad transitions.
I am not an expert, but probably: drm/radeon: use gart memory for DMA ring tests; could be the good commit.
That should have no effect once the driver is initialized. None of the changes between rc1 and rc2 seem like obvious candidates.