[BUG] Fails to Wake Displays with Specific Configurations #1772
Description
My monitor sometimes fails to start from sleep when DisplayPort version 1.2 is enabled in its settings menu. This is not a significant issue for me, as I can revert to DP 1.1, but it may indicate a larger problem.
The monitor, a Dell U2715H monitor that uses DP 1.1 by default, supports DP 1.2, but I need to enable it in the monitor's menu.
I noticed that when DP 1.1 is enabled, everything works great, but when DP 1.2 is used, both Cosmic Comp and Niri sometimes fail to turn it back on after sleep, suspend, or TTY switch. Once this wake issue has occurred, restarting the compositors doesn't always resolve the problem, as if something becomes corrupted at the kernel level.
Update: The issue still occurs in DP 1.1, but much less often.
Note: Logging into a KDE Plasma session (or sudo sddm) will revive the monitor 100% of the time, but switching TTY to plasma from a comp using smithay does not.
I suspect that Smithay may be failing to properly get/use the proper configuration for specific monitors when using NVIDIA graphics. I guess that for my Dell monitor, it continues sending a signal at 1.1 frequencies even though the monitor is expecting 1.2 frequencies, so it will fail to start.
If that's the case, then this may be causing some of the documented monitor wake issues with NVIDIA graphics on both Cosmic and Niri:
- [BUG] Does not allow to enable laptop display on multiple monitors pop-os/cosmic-epoch#431
- NVIDIA graphics meta-issue pop-os/cosmic-epoch#168
- Bug: oryp5 w/2060: suspend causes external display to be blank until machine is rebooted pop-os/cosmic-comp#1454
- Main laptop monitor disabled after closing lid YaLTeR/niri#996
- https://www.reddit.com/r/pop_os/comments/1kzhh3e/cosmic_alpha_7_monitors_and_kvm/
- etc