Screen flicker after wake from sleep on Intel Skylake GPU (i915)
I have an HP ProBook 440 G4 laptop with integrated Intel HD Graphics 520 (skylake) GPU, using the i915 driver, X11 display server, issue occurs in both KDE Plasma and i3 desktop environments.
For context, I tried a Linux Mint 22.2 + cinnamon install before arch, and the flickering would appear as soon as the display manager booted into the login screen, I messed around with different kernel parameters like enable_psr, fastboot, enable_fbc and restarted. Except for nomodeset (which works because it's the software renderer), none of the previous parameters changed the behavior noticeably.
After manually installing arch, i set up both plasma and i3, started the session with startx and it worked fine until the pc was put on sleep mode, after that, the flicker would be the same as before. Given that it persisted across i3, plasma and cinnamon tells that obviously the desktop environment has nothing to do with it.
I do believe that the display/login manager might have something to do with it, since doing sudo start plasmalogin.service either inside a plasma session or before startx triggers the flickering immediately.
I've seen related issues in arch but they always involve AMD or nvidia gpus, and the fix comes down to driver updates.