Failing to resume from suspend on AMD Zen 2 machine

[Alex Dewar]

Hi,

I'm running an AMD desktop machine (Zen 2). At some point suspend and
resume worked fine, but a few releases ago, something broke and now it
fails to resume. I should probably have sent a message as soon as I
noticed, but I've been getting by without it and figured it might
resolve itself anyway.

What happens is that the system appears to suspend fine, but when I
press the power button it *seems* to briefly wake (the LED stops
flashing and the fans start) but then it goes back into a suspended
state (fans stop, LED starts blinking). If I then press the power
button again, it powers up and I can see my lockscreen, but the system
is not responsive to user input.

This problem happens *almost* every time I suspend, however, if I've
only recently booted the system and just have a few processes running
(i.e. my window manager and normal system services) then it suspends
and resumes fine. If I then open a browser etc. then it stops working.

What extra info can I provide you with to make this a useful bug
report? (I also have an AMD GPU -- maybe that's the culprit?)

I'm running the stock Arch Linux kernel (v6.15.7). I also tried the
latest commit on mainline (2942242dde89) but had the same result.

Best,
Alex