blymn@baesystems.com.au said:
> You _could_ assign differing priorities to the leaf devices so that
> the powerhooks for these devices get run before the bus devices which
> would be at a lower priority

This would be complex in case of deeper bus-device-bus hierarchies
as with PCI and USB.
And, the bus must be sure that _all_ its devices cooperate on
a state change. Device drivers could call back to the bus to tell,
but then we'd have a mix of both worlds which doesn't make it easier.

best regards
Matthias