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

[From: Nils Faerber]

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Igor Stoppa schrieb:
> On Thu, 2006-01-12 at 15:55 +0100, ext Florian Boor wrote:
>>Igor Stoppa wrote:
>>>Only Retu can wake up the device from poweroff state at a preset time;
>>>unfortunately this is the time resolution that it canprovide. In order
>>>to extend alarms and events scheduling one could have the daemon
>>>scheduling periodic wakeups (every 24h) till the real alarm is closer
>>>than 24h.
>>i'm not that familiar with the power states of the 770. Does it actually reach
>>"poweroff" during normal use without turning it off with the power switch?
> 
> Nope. Omap has basically idling states:
> -arm idle
> -big sleep
> -deep sleep
> 
> and which one is reached at a certain time depends on which
> peripherals/clocks are active.
> 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.

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.

>>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 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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