Re: Attempted summary of suspend-blockers LKML thread

From: david
Date: Thu Aug 05 2010 - 21:03:21 EST

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). ÂFor 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?

David Lang