Re: [PATCH 1/8] PM: Opportunistic suspend support.

Dmitry Torokhov
2010-05-27T18:13:46Z

On Wed, May 26, 2010 at 05:52:40PM -0700, Arve Hjønnevåg wrote:
> 2010/5/26 Alan Stern <stern@rowland.harvard.edu>:
> > On Wed, 26 May 2010, Arve Hjønnevåg wrote:
> >
> >> > I must be missing something.  In Arve's patch 1/8, if the system is in
> >> > opportunistic suspend, and a wakeup event occurs but no suspend
> >> > blockers get enabled by the handler, what causes the system to go back
> >> > into suspend after the event is handled?  Isn't that a loop of some
> >> > sort?
> >> >
> >>
> >> Yes it is a loop. I think what you are missing is that it only loops
> >> repeatedly if the driver that aborts suspend does not use a suspend
> >> blocker.
> >
> > You mean "the driver that handles the wakeup event".  I was asking what
> > happened if suspend succeeded and then a wakeup occurred.  But yes, if
> > a suspend blocker is used then its release causes another suspend
> > attempt, with no looping.
> >
> >> > And even if it isn't, so what?  What's wrong with looping behavior?
> >>
> >> It is a significant power drain.
> >
> > Not in the situation I was discussing.
> >
>
> If you meant it spend most of the time suspended, then I agree. It
> only wastes power when a driver blocks suspend by returning an error
> from its suspend hook and we are forced to loop doing no useful work.
>

If driver refuses to suspend that means there are events that need
processing. I fail to see why it would be called "looping doing no
useful work".

--
Dmitry