[linux-pm] Re: Power Mangement Interfaces

[Woodruff, Richard]

> As you know we want user configuration of enabled wakeup events (unlike
> embedded platforms where this is hardcoded). It seems that the current
> interface available for that is /sys/devices/../power/wakeup hook (when
> !ACPI).
> 
> However there are several wakeup capable devices in OLPC which do not
> have drivers, thus no platform devices:
> 
> - power button
> - lid
> 
> It seems that creating platform devices for these two just for the
> purpose of a having an interface for enabling wakeup events is overkill.
> 
> Given that, we probably want something similar to what was initially
> described in http://wiki.laptop.org/go/Power_Management_Interface ?
> 
> The downside of doing that is a non-unified interface: platform
> devices via /sys/devices/../power/wakeup and otherwise
> /sys/whatever/wakeup/source?
 
Perhaps it is over kill, but is it really very expensive for handful of devices?  I am curious as to others experiences here.

In hacks for embedded in the past I've sprinkled some extra device/bus registrations around to provide a common way to enable wake ups and idle states.  I don't know that it was the best way to do it, but it could be made to work.

A dev structure is a handy thing to have around and provides symmetry.  Having a sysfs entry provides for an easy way to set and test from user space.  You can always export the function in the kernel also to get a secondary path to the function.  All that seems nicer than adding ioctrls and the like per driver.

Regards,
Richard W.