[maemo-developers] [maemo-developers] Maemo Alarm/Notifier Interface

[From: Igor Stoppa]

On Fri, 2006-01-13 at 16:11 +0100, ext Nils Faerber wrote:
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> Igor Stoppa schrieb:
[snip]
> > Obviously they have different wakeup latencies but all of them are
> > insignificant, when compared to the delay that would be introduced by a
> > traditional suspend-to-disk, which is the closer state to the "poweroff"
> > that youu are mentioning. 
> 
> Well, power-off is something like shutdown in the first place, not
> necessarily connected to suspend to disk - you could simply reboot the
> device loosing your state.
That's not really desired in a consumer device.
> 
> But as someone ales already pointed out I would also accept and even
> expect that a device that is switched off (770 power button -> switch
> off) will indeed keep being switched off despite of any occuring alarms.
> The user should know what he does when switching off his/her device. So
> I think we can basically ignore the power off problem and concentrate on
> the other above mentioned power/sleep states.
> 
Again, we are talking about something that is actually meant to be sold,
so it has to behave nicely. Personally I like to have my alarms to be
fire & forget. What's the point of setting an alarm if I have to
remember to take care of the thing that should remind me of it?

Even if we can achieve roughly 10 days of standby time, that's not much
compared to the power saving that can be achieved by effectively
switching off the device over very long periods of inactivity.
That would be compromised by such an approach of delivering alarms only
when the device is on.

These small details make the difference between a "device for hackers
only" and a device that can leverage the benefits of running linux and
yet provide a good user experience even to the regular users.

> >>As long as there is such a timer which can be used that would be fine. Sounds a
> >>little bit similar to what we do on the iPAQ.
> > I used generic terms, but the Omap RTC is what I had in my mind.
> > However this fine-grained resolution would be lost when the device is
> > _really_ off and the usual trick to wake up and wait would be required.
> > 
> > And the RTC has to be added to the list of wakeup sources that can
> > trigger the transition from any sleep state to running.
> 
> That is just a bit in some regsiter - a very trivial kernel
> modification. The more problem would be to write an OMAP RTC compatible
> driver for the 1710 (if not yet existent, which it IMHO is not) since
> there is not documentation for the 1710 publically available.
I checked it some time ago for a basic wakeup functionality and apart
for a few changes that functionality was already provided.
> 
> I wrote the first SA1110 RTC driver and this was pretty easy given you
> have the docs. After toggling the wakeup source register bit for RTC we
> had proper wakeup alarms on the iPaq ;) This was basically one weekend's
> work without prior experience with RTC code. No big deal.
> Next was RTC support for atd, or in fact Rus Nelson started a
> specialised small scale atd for iPaq and then RTC was added to it. This
> forms the alarm framework for Familar Linux.
> 
> Cheers
>   nils faerber
> 
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-- 
Igor Stoppa (Nokia M - OSSO / Tampere)