Currently, devices connected via xhci do not work after resume.
In some cases, this is the only thing missing for a flawless resume experience.
Since xhci is widespread, this will greatly improve laptop user experience.

nia has added another $100 on to maya's bounty on the condition of perfect suspend on their Lenovo X250, because this is the only blocker for that in -9. see PR 56050

abs added another $200 for working suspend/resume on a Thinkpad T480 (-current resume does not complete - it prints a few "WARNING: TSC time went backwards by 2650670841" type lines, not sure of -9 state).