Re: [RFD] Automatic suspend

Rafael J. Wysocki
2009-02-16T23:02:36Z

On Monday 16 February 2009, Alan Stern wrote:
> On Mon, 16 Feb 2009, Rafael J. Wysocki wrote:
>
> > OK, so I think there are two things that user space may be allowed to do as
> > far as putting devices into low power states is concerned:
> > * disable/enable the automatic power management of the device (provided that
> > the driver supports the automatic PM)
>
> Set the automatic PM parameters (idle timeout, state to go to, etc.).

Yes. I'm not sure about the state part, though.

> And disabling automatic PM altogether (effectively the same as setting
> the idle timeout to infinity).

Yes.

> > * check what power states devices are in.
>
> What about situations where we want to distinguish between the power
> state of the device itself and the power state of the link? For a disk
> drive we may want to power the link on and off quite a lot, as that
> has low latency, but spinning the disk up and down takes a long time
> and so should have a longer idle-time value.

Well, I'm not sure at the moment.

Do you have any suggestions?

Rafael