Re: [PATCH 05/11] PM: Enable early suspend through /sys/power/state

Pavel Machek
2009-02-02T11:45:14Z

On Fri 2009-01-30 19:13:32, Arve Hj?nnev?g wrote:
> On Wed, Jan 28, 2009 at 11:34 AM, Pavel Machek <pavel@ucw.cz> wrote:
> > Hi!
> >
> >> If EARLYSUSPEND is enabled then writes to /sys/power/state no longer
> >> blocks, and the kernel will try to enter the requested state every
> >> time no wakelocks are held. Write "on" to resume normal operation.
> >
> > No, please don't break compatibility like this. You changed semantics
> > of 'mem'...
> >
> > Just add another two states, for example "auto-mem" and
> > "auto-standby", and make them enter mem/standby when required.
> >
>
> What would you want to happen if someone writes "mem"? If we just call
> enter_state, it will fail and return an error if a wakelock is
> locked.

That would be fine. And ignoring wakelocks in this case would be even better.

> We can call request_suspend_state and then wait for another thread to
> write "on", but this still requires user-space changes to work
> correctly. If the goal is to allow the kernel to be compiled with
> wakelock and early suspend support while preserving the old behaviour
> if wakelocks are not used, then the first option is better.

Yes, goal is that compiling in wakelock / early suspend support has
no effect on existing functionality.
Pavel
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