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    SubjectRe: Attempted summary of suspend-blockers LKML thread
    On Thu, 5 Aug 2010, Brian Swetland wrote:

    > On Thu, Aug 5, 2010 at 4:03 PM, Paul E. McKenney
    > <paulmck@linux.vnet.ibm.com> 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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