Re: [PATCH 01/13] PM: Add wake lock api.

Uli Luckas
2009-02-06T09:45:21Z

On Friday, 6. February 2009, Arve Hjønnevåg wrote:
> On Thu, Feb 5, 2009 at 1:11 AM, Pavel Machek <pavel@ucw.cz> wrote:
> > On Wed 2009-02-04 18:50:14, Arve Hj??nnev??g wrote:
> >> +A locked wakelock, depending on its type, prevents the system from
> >> entering +suspend or other low-power states. When creating a wakelock,
> >> you can select +if it prevents suspend or low-power idle states. If the
> >> type is set to
> >
> > idle states are very different from suspend. Mixing them does not look
> > like good idea... and IIRC we already have API somewhere to prevent
> > deep idle states. Intel did it for their wireless cards IIRC.
>
> If you are talking about the pm_qos interface, then yes there is some
> overlap. We did not use the pm_qos interface since it does a linear
> scan for a string every time you change a requirement, and it only let
> you specify the latency you need not the power level. We have
> interrupts that stop working at the lowest power level and this does
> not easily translate into a latency value.
>
> >> + Key pressed Key released
> >> + | |
> >> +keypad-scan ++++++++++++++++++
> >> +input-event-queue +++ +++
> >> +process-input-events +++ +++
> >> +
> >
> > I'm not sure if keyboard scanning example is good here. It is very
> > t-mobile G1 specific.
>
> There is no G1 specific code in the keypad driver. I also don't
> remember seeing any development boards without a similar keypad. I
> like this example since it show how an event can be passed from the
> kernel to user-space.
>
I absolutely agree. The example shows how you can keep wake locks right from
the time the interrupt comes in through all levels until a user space action
gets triggered.

Uli

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