Subject: Re: merge of freebsd eventhandler
To: Brett Lymn <>
From: Matthias Drochner <>
List: tech-kern
Date: 05/27/2006 16:43:40 said:
> +.Fn powerhook_establish "void (*fn)(void *a, int why)" "void *arg" 

Imho hooks initiated by individual drivers are not the way
to go for power management in the future. Power management
requests should travel along the device tree instead.
Two reasons:
-Things on a bus depend on each other. So eg one can't enter
 state B2 on a PCI bus (means "clock stopped") if not all
 devices on the bus support D2 or D3hot (where D3hot might
 be out of question for other reasons). Also, budgeting
 for standby power and enabling of wakeup events must be
 done centrally.
-There is no namespace generic enough for the "why" arguments
 telling the devices which state to enter. The SOFTSUSPEND
 etc might be good enough for the user interface, but drivers
 need more specific directions which are bus dependant.

best regards