https://bugs.freedesktop.org/show_bug.cgi?id=76564
--- Comment #69 from Christian König deathsimple@vodafone.de --- Hi Peter & Jereon,
please give this commit a try: http://cgit.freedesktop.org/~deathsimple/linux/commit/?h=drm-fixes-3.15-wip&...
It should now use the pflip irq to avoid problems with missed flips.