Comment 11 for bug 1347776

(In reply to comment #1)
> Note that, due to a firmware change, the m400 rule should use "gpio_keys"
> instead of "gpio-keys". Here is the new rule:
>
> SUBSYSTEM=="input", KERNEL=="event*", SUBSYSTEMS=="platform",
> KERNELS=="gpio_keys.6", PROGRAM="/bin/grep '^HP ProLiant m400 Server
> Cartridge$' /proc/device-tree/model", TAG+="power-switch"

That's a neat hack, but in no way upstreamable.

Upstream udev dev will not read the device information from /proc, and will
also not call any external tools like grep.

This all needs to be solved properly on the kernel side, to export real devices
and allow efficient and reliable matching from userspace tools.