Messages in this thread | | | Date | Wed, 27 Apr 2011 00:06:53 +0200 | From | Pavel Machek <> | Subject | Re: [RFC PATCH v2 1/3] PM / Core: suspend_again callback for device PM. |
| |
Hi!
> > It certainly looks a lot like s2ram to the user. > > > > Now, your PC wakes up periodically in s2ram, too; but it is keyboard > > controller that wakes up, not CPU, so you do not know. > > I seriously doubt it's a keyboard controller in contemporary machines.
> Yes, there are parts of them that don't actually sleep, but that's not > under OS control.
Ok, so it is called "embedded controller" these days. But you got the idea.
> > On Zaurus, you do not know, either; nothing visible happens and > > userspace is shielded from these details. > > If you wake up device drivers, it _is_ visible. Maybe not to user > space, but that's a semantic difference.
Just to clarify; not _all_ device drivers need to be woken up. Just SPI + charger code is enough... and I guess it would be prefered because spinning up disk just to toggle charger would be nasty.
> > Should user really have to know if battery charger is implemented on > > keyboard controller or on main cpu before he selects which interface > > to use? > > Please don't confuse user space with the user. You can resume all the > way to user space without turning the backlight on and the user will not > notice, right?
The user has to type "echo mem > /sys/power/state" :-). And you better turn him the backlight on, typing blind is bad.
Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
| |