Comment # 10 on bug 1190854 from Hadrien Grasland

This problem was fixed by the Linux 5.15 update!

The BAR allocation error remains, but the power management error has gone away,
suggesting that the latter was the culprit after all.

All previously configured firmware hacks (disabling resizable BARs, forcing
mapping to lower 32-bit adresses) can be removed while keeping the graphics
configuration working as expected.