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

Rafael J. Wysocki
2010-05-27T19:58:47Z

On Thursday 27 May 2010, Dmitry Torokhov wrote:
> 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".

I guess Arve meant the case of events that didn't propagate to user space.

Rafael

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