Comment # 12 on bug 100289 from OmegaPhil@startmail.com

I have reached this again, and can confirm that even with a kernel boot
parameter of 'drm.debug=0x01', when I get '(WW) RADEON(0): flip queue failed in
radeon_scanout_flip: Invalid argument' in Xorg.log, there is no mention of
'flip target' in the drm output.

I'm going to test with TearFree off to show that its definitely to blame.