https://bugs.freedesktop.org/show_bug.cgi?id=97969
--- Comment #8 from Nicolai Hähnle nhaehnle@gmail.com --- Now that I actually got to test this on radeon rather than just amdgpu, the problem was pretty obvious. It's fixed for me with https://patchwork.freedesktop.org/patch/113573/. I apologize for the inconvenience.