On Saturday, August 07, 2010, david@xxxxxxx wrote: > On Sat, 7 Aug 2010, Mark Brown wrote: > > > On Fri, Aug 06, 2010 at 04:35:59PM -0700, david@xxxxxxx wrote: > >> On Fri, 6 Aug 2010, Paul E. McKenney wrote: ... > What we want to have happen in an ideal world is > > when the storage isn't needed (between reads) the storage should shutdown > to as low a power state as possible. > > when the CPU isn't needed (between decoding bursts) the CPU and as much of > the system as possible (potentially including some banks of RAM) should > shutdown to as low a power state as possible. Unfortunately, the criteria for "not being needed" are not really straightforward and one of the wakelocks' roles is to work around this issue. > today there are two ways of this happening, via the idle approach (on > everything except Android), or via suspend (on Android) > > Given that many platforms cannot go to into suspend while still playing > audio, the idle approach is not going to be able to be eliminated (and in > fact will be the most common approach to be used/deugged in terms of the > types of platforms), it seems to me that there may be a significant amount > of value in seeing if there is a way to change Android to use this > approach as well instead of having two different systems competing to do > the same job. There is a fundamental obstacle to that, though. Namely, the Android developers say that the idle-based approach doesn't lead to sufficient energy savings due to periodic timers and "polling applications". Technically that boils down to the interrupt sources that remain active in the idle-based case and that are shut down during suspend. If you found a way to deactivate all of them from the idle context in a non-racy fashion, that would probably satisfy the Android's needs too. Thanks, Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
