Created attachment 847526 [details]
Hardware info

This bug doesn't occur on Leap 15.2 but it happens very consistently on
Tumbleweed.

How to reproduce:
1) Connect an external screen by HDMI *after* turning on the computer

Expected behavior:
The screen is recognized

Actual behavior:
Both screen go blank and the system is unusable

If the screen is connected before turning on the computer then it will work as
expected, but if it's re-plugged it will still hang.

This isn't a desktop environment specific issue and it happens even without any
X server at all.

Speculation:
This is most likely a kernel issue, specifically a bug in the i915 driver. If
so, it was introduced between Linux 5.3 and 5.11.

Things that were tried:
i915.enable_psr=0 still, intel_idle.max_cstate=1 and i915.enable_dc=0 where all
tried but the bug still occur.
Tried to get a dump with kdump but nothing was written in /var/crash.

Any tips to debug this issue so it can be narrowed down would be really
helpful. I'm currently trying to find a way to test every kernel from 5.3 to
5.11 without having to actually compile them on tumbleweed, so it can, without
a doubt confirmed it's a kernel issue and also find the version on which the
regression was introduced.