Regression: mt7921e unable to change power state from d3cold to d0 - 6.12.x broken, past LTS 6.6.x works

[Sergio Callegari <sergio.callegari@gmail.com>]

There is a nasty regression wrt mt7921e in the last LTS series (6.12). 
If your computer crashes or fails to get out of hibernation, then at the 
next boot the mt7921e wifi does not work, with dmesg reporting that it 
is unable to change power state from d3cold to d0.

The issue is nasty, because rebooting won't help.

The only solution that I have found to the issue is booting a 6.6 
kernel. With that the wife gets alive again. If, at this point, you boot 
into 6.12, everything seems to be fine again, until a boot fails and 
from that moment on you are without wifi.

Working around the issue is not very discoverable. On my machine not 
even a hardware reset (40s of power off button pressed) helped alone, 
without going through the 6.6 kernel boot.

I think the regression was introduced with 6.12 and I remember having no 
issues with previous kernels, but cannot be 100% sure.

Similarly, I do not know if the bug is with the wifi card driver itself 
or with something related to PM or PCIe.

The machine on which I am experiencing the issue is an Asus ROG 14 
laptop (2022 edition), with AMD CPU and GPU.

Thanks for the attention,
Sergio