Comment # 91 on bug 106175 from tempel.julian@gmail.com

I suppose I could narrow down the culprit:
The issue does not occur with stable version 18.1.0 of xf86-video-amdgpu DDX
driver.
But it does occur with both xorg modesetting and latest git commit of
xf86-video-amdgpu.

I'll try to find the faulty commit of the xf86 DDX driver.