I should have said "the only possible userspace solution". Strictly speaking it's the Intel kernel driver at fault for advertising DRM_CAP_ASYNC_PAGE_FLIP as supported and then rejecting it as invalid in some configurations. The driver has to do that because of hardware limitations, but still chooses to advertise the feature as supported because it's usually supported :S
I should have said "the only possible userspace solution". Strictly speaking it's the Intel kernel driver at fault for advertising DRM_CAP_ ASYNC_PAGE_ FLIP as supported and then rejecting it as invalid in some configurations. The driver has to do that because of hardware limitations, but still chooses to advertise the feature as supported because it's usually supported :S