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

[From: Igor Stoppa]

On Thu, 2006-01-12 at 15:55 +0100, ext Florian Boor wrote:
> Hello,
> 
> 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. 
> 
> > The granularity problem could be overcome using either a sw timer or an
> > internal HW timer, with better resolution than 1m.
> > It would be programmed by the daemon, after the last wakeup and  before
> > reaching the scheduled time for the event.
> 
> 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.

> Greetings
> 
> Florian
> 
-- 
Igor Stoppa (Nokia M - OSSO / Tampere)