Monitors no longer sleep properly on my system (dual monitor connected
via DP->DVI, amdgpu, x86_64). The monitors slept properly on 5.14, but
stopped during the 5.15 series. I have also filed this bug on the kernel
bugzilla[0] and downstream[1].
I have performed a bisect, first "bad" commit to master is
55285e21f04517939480966164a33898c34b2af2[1], the same change made it
into the 5.15 branch as e3b39825ed0813f787cb3ebdc5ecaa5131623647. I have
verified the issue exists in latest master
(a51e3ac43ddbad891c2b1a4f3aa52371d6939570).
Steps to reproduce:
1. Boot system (Fedora Workstation 35 in this case)
2. Log in
3. Lock screen (after a few seconds, monitors will enter power save
"sleep" state with backlight off)
4. Wait (usually no more than 30 seconds, sometimes up to a few minutes)
5. Observe monitor leaving "sleep" state (backlight comes back on),
but nothing is displayed
[0] - https://bugzilla.kernel.org/show_bug.cgi?id=215203
[1] - https://bugzilla.redhat.com/show_bug.cgi?id=2028613
