[alsa-devel] Audio Miniconference 2013 schedule - Edinburgh 21st October

Mark Brown broonie at kernel.org
Mon Oct 7 19:44:48 CEST 2013

On Mon, Oct 07, 2013 at 10:22:42AM -0700, Patrick Lai wrote:

> Lately, there has been a lot of emphasis on reducing cold start latency
> which audio hardware path setup takes up good chunk of time. I found
> DAPM takes up quite a bit of time finding path to enable. In addition,

What are the problems you're seeing here?  This used to be a big
problem for modern CODECs with big sets of widgets and routes but the
optimisations I did a while back (which made it into v3.4 so I think
everyone is using them now) and the work that Tsutsui-san did in v3.10
on improving the graph reset got it reasonably under control for the
systems that I was aware of having trouble.

The commits from Tsutsui-san were:

   0e669246dcd1 ASoC: dapm: Remove redundant clear_walk() for supply widgets 
   1059ecfa0f1e ASoC: dapm: Only clear paths we've walked

(mainly the second one).

> DPCM could be enhanced to save on cold start latency by enabling
> front-end & back-end in parallel if underlying hardware can support it.

Hrm, nobody mentioned any problems with CPU side startup times
previously.  What exactly is taking the time with this stuff - is it
something that could be pushed into DAPM and use what's there already
(or alternatively then be optimised and used for CODECs too)?

> I would like to see if we can have some discussion on optimization.

Well volunteered :)
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