Created attachment 143150 [details]
Xorg.0 log with DC off

I'm running Solus KDE with kernel 4.20.2 but I've had these issues since kernel 4.19. Here's the list of issues with AMDGPU DC enabled:
- With Solus' default kernel flags I have wrong DisplayPort enumeration, meaning that I get DisplayPort-1 when I turn on the computer, and then DisplayPort-2 when I get my monitor to sleep and then I wake it up.
- If I put my computer on sleep (suspension) and then wake it up, I cannot set a usable refresh rate. This means I actually get 40 Hz when I set 60, and 45 Hz when I set 74 (yeah, I have a bit of screen "overclocking". That's how I found DisplayPort enumeration is wrong).
- I get microstuttering, particularly noticeable when I drag windows around.

Now, all these issues are non existant if I set the amdgpu.dc=0 kernel flag. Also, DisplayPort number is DisplayPort-0 under any circumstances.

❯ inxi -G
Graphics:  Device-1: AMD Hawaii PRO [Radeon R9 290/390] driver: amdgpu v: kernel 
           Display: x11 server: X.Org 1.20.3 driver: amdgpu,ati unloaded: fbdev,modesetting,vesa 
           resolution: 1920x1080~60Hz 
           OpenGL: 
           renderer: AMD Radeon R9 200 Series (HAWAII DRM 3.27.0 4.20.2-107.current LLVM 7.0.0) 
           v: 4.5 Mesa 18.3.1