On Thu, Aug 5, 2010 at 6:01 PM, <david@xxxxxxx> wrote: > On Thu, 5 Aug 2010, Brian Swetland wrote: >> On Thu, Aug 5, 2010 at 5:16 PM, <david@xxxxxxx> wrote: >>>>> >>>>> 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. >> >> Obviously not all clocks are stopped (the DSP and codec are powered >> and clocked, for example), but yeah we can clock gate and power gate >> the cpu and most other peripherals while audio is playing on a number >> of ARM SoC designs available today (and the past few years). > > does this then mean that you have multiple variations of suspend? > > for example, one where the audio stuff is left powered, and one where it > isn't? While the cpu (and the bulk of the system) is suspended, it's not uncommon for some peripherals to continue to operate -- for example a cellular radio, gps, low power audio playback, etc. Details will vary depending on the SoC and board design. It's not so much a different suspend mode (the system is still suspended), just a matter of whether a peripheral can operate independently (and if it is lower power for it to do so). Brian _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
