Adding a delay to prevent "Unsafe Shutdowns" for nvme drive

[josch]

We just had a conversation on MNT Reform on libera.chat IRC that touched this subject. Sigrid agreed that I copypaste what she said to this post:

21:04 < sigrid> also on a note related to lpc driver. as I understood it’s not setting pm_power_off? would probably make sense to do that, so the systemd shutdown hack isn’t needed
21:04 < sigrid> it would also work for distros that have none of that, like Void
21:09 < josch> sigrid: what does writing xPWR0 to /dev/hidraw* do exactly?
21:09 < sigrid> it asks the keyboard to write to lpc over spi to shut off power rails, which lpc does
21:10 < sigrid> it doesn’t give the chance for the kernel to issue a full shutdown of all devices, I believe, including nvme
21:10 < sigrid> hence that post in community about unsafe shutdowns on nvme, which I could also see here with 9front (but that’s because 9front doesn’t tell nvme it’s shutting down yet)
21:12 < sigrid> since that lpc driver module isn’t built into the kernel, I think it should be able to override pm_power_off, which by default will probably be set to something that does not really work on reform
21:13 < sigrid> don’t think arm trusted firmware knows how to ask lpc to turn everything off, anyway

Maybe this is also interesting for @nanocodebug as the maintainer of the reform lpc module.

Currently, we use this systemd hack to turn off the unit: Files · main · Reform / MNT Reform Tools · GitLab