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DisplayPort connected monitor wakes from DPMS sleep with a blank screen

Brief summary of the problem:

On both Plasma and GNOME Wayland after I lock the screen and my monitor goes into sleep mode, about 10-15 seconds later the monitor wakes up on its own and shows a blank screen; only the backlight is on.

I noticed that after the monitor sleeps, the graphics card seems to "turn off" (the red RADEON light on my card turns off). A few seconds later, just prior to the monitor waking, the RADEON light turns back on and the display wakes with a blank screen until you move the mouse or do something to get the lock screen to display.

Since I thought this may be power management related, I added the following kernel option:

amdgpu.runpm=0

This seems to resolve the issue. The RADEON light on my card stays on and the display stays asleep.

I'm not exactly sure what would help troubleshoot this, so please let me know what logs or other information is needed to help debug.

I think this is what's happening based on my observation:

  1. DPMS signal is sent to monitor.
  2. Monitor goes into "deep-sleep", which drops the DP link. (as I understand it, LG monitors are notorious for this)
  3. amdgpu thinks nothing is connected to the card, so it turns it off (hence the relation to runpm).
  4. The monitor detects that something changed with DP and tries to renegotiate.
  5. Something bugs in amdgpu and the card turns back on, monitor turns back on, and you get a blank screen.

Hardware description:

  • CPU: Ryzen 7 5800X
  • GPU: [AMD/ATI] Navi 22 [Radeon RX 6700/6700 XT / 6800M] [1002:73df] (rev c1)
  • System Memory: 16GB
  • Display(s): LG 34GP83A-B
  • Type of Display Connection: DisplayPort

System information:

  • Distro name and Version: Arch Linux
  • Kernel version: 5.15.10-arch1-1
  • Custom kernel: N/A
  • AMD official driver version: N/A