I suffered pretty much all of the issue listed in this thread for many weeks
since upgrading to 3 1440p monitors.

I have an Club 3D R9 390 Royal Queen.

Comment #182 best describes the problem I faced and what I had to do to work
around it.

I am happy to announce that kernel 4.16.7 has solved this issue for me.

My system has no more issues booting. KDE is stable. No flickering at all. Even
when forcing power_dpm_force_performance_level to 'low'.

I'm running Gentoo with:
mesa-18.1.0
libdrm-2.4.91
xf86-video-amdgpu-18.0.1
xorg-drivers-1.19

kernel params include: radeon.cik_support=0 amdgpu.cik_support=1
amdgpu.modeset=1 amdgpu.dc=1 amdgpu.dpm=1

If anyone needs more info please ask.

What	Removed	Added
Resolution	---	WORKSFORME
Status	REOPENED	RESOLVED