The first question is where do the latency timer values
get stored?  If they are stored in one of those devices
that has a limited number of write cycles, then we want
to avoid writing them unless we are changing them.

I think it would be useful if pcictl(8) could write
the latency timer values as well as read them.
This would allow for admins to experiment with tuning
them with having to hack the kernel source and reboot.