I might have found a solution, but I am suspicious and have not tested it fully yet.
To summarise: Arch/Artix linux, KDE. Severe screen flickering, wallpaper appears black, windows don’t update until you resize them.
- Kernel modesetting (aka KMS; i.e. removing
xf86-video-intel etc - see above posts) doesn’t work because X11 claims it can’t find the video device.
- XFCE has the same issue.
- Using Wayland results in a static black screen.
…but this black screen is actually due to a bug in the .desktop file KDE Plasma registers in /usr/share/wayland-sessions that e.g. LightDM picks up on.
It turns out this black screen is because plasma-dbus-run-session-if-needed is buggy.
In the file /usr/share/wayland-sessions/plasma.desktop, there is an Exec= like like so:
Exec=/usr/lib/plasma-dbus-run-session-if-needed /usr/bin/startplasma-wayland
To fix the issue, replace that line with this one:
Exec=/usr/bin/dbus-run-session /usr/bin/startplasma-wayland
…this forces it to start dbus and then kick plasma into working on Wayland. You will need to reboot for the changes to take effect, or else restart LightDM/your greeter.
If you are not running KDE, then there will likely be another .desktop file in /usr/share/wayland-sessions that you need to edit.
Even better, because wayland bypasses X11 and xf86-video-intel and do KMS, it appears to function normally. However, given the amount of trouble I have had I’m suspicious. I’m going to run some graphical application tests, but does anyone know how to tell if the iGPU is being used or whether software rendering is being used instead?
Finally, I haven’t tested XWayland yet, but somehow I doubt it will function correctly in my circumstances.
Ref https://forums.gentoo.org/viewtopic-t-1164094.html?sid=67afc8babb1469144eff8916345214f3, but this was difficult to find given the symptoms my system was/is exhibiting, so posting here too.