Kyle, I had applied both fd.o git 295823d0879a5b574bb79843a6acd43adb9259e5 (radeon: Default to leaving AGP transfer mode and fast writes unchanged) and c54a31565e3ea50f1af7b81b1bf0c0e437099f47 (radeon: fixup fastwrites to be always off). I believe your patch was one line taken from the latter. Do you think AGP mismatch is fine as long as one turns off fastwrites?
(for completeness, my test package also had f5ffb9fb3bdd7cec020240c5831ae92ee744972c (ati: fix detection of some newer radeons using ati wrapper) for bug #28925, which came in the official 1:6.6.2-0ubuntu5) -- [regression][rv280] black screen and console freeze when X starts - drm lockup https://launchpad.net/bugs/67487 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
