Re: Attempted summary of suspend-blockers LKML thread

[david]

On Thu, 5 Aug 2010, Brian Swetland wrote:

> On Thu, Aug 5, 2010 at 4:03 PM, Paul E. McKenney
> <paulmck@xxxxxxxxxxxxxxxxxx> wrote:
> > > > so what would wake a phone up from suspend where the phone should go back to
> > > > sleep in under a second?
> > >
> > > Here are some real-world examples from shipped android devices:
> > > - battery gauging happens every 10 minutes, need to wake long enough
> > > to chatter with the 1w interface and make sure the battery is not
> > > exploding
> > > - always on mail/im/calendar/etc sync often has network events that
> > > happen every 5-10 minutes which cause devices to briefly wake up and
> > > return to sleep
> > > - gps tracker app might wake every couple minutes or every n gps
> > > events to log location
> > > - low power audio subsystems can wake you up every 1-4 seconds (pcm)
> > > or 1-4 minutes (mp3) to fetch more data
> >
> > Interesting!
> >
> > So for an mp3 playback, does an Android suspend between data fetches?
>
> It can if the latency is long enough (which is why I point out low
> power audio which is usually high latency).  For low latency (system
> sounds, etc) 10-25ms between buffers it's not practical to fully
> suspend but we will go to the lowest power state in idle if possible.

the playback is able to continue even with all the clocks stopped? that 
surprises me. I would hav expected it to be able to sleep while playing 
audio, but not do a full suspend.

David Lang
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