https://bugs.freedesktop.org/show_bug.cgi?id=67107
--- Comment #15 from Alex Deucher agd5f@yahoo.com --- Does this branch work any better? http://cgit.freedesktop.org/~agd5f/linux/log/?h=drm-next-3.13-wip please also try cherry-picking this commit as well: http://cgit.freedesktop.org/~agd5f/linux/commit/?h=drm-fixes-3.12&id=407...
Also, does vgaswitcheroo not work for you? Why are you manually messing around with acpi methods?