[alsa-devel] [PATCH 2/2] ASoC: Do DAPM control updates in the middle of DAPM sequences

Peter Ujfalusi peter.ujfalusi at nokia.com
Thu Dec 16 14:51:13 CET 2010

On Tuesday 14 December 2010 19:53:22 ext Mark Brown wrote:
> Attempt to minimise audible effects from mixer and mux updates by
> implementing the actual register changes between powering down widgets
> that have become unused and powering up widgets that are newly used.
> This means that we're making the change with the minimum set of widgets
> powered, that the input path is connected when we're powering up widgets
> (so things like DC offset correction can run with their signal active)
> and that we bring things down to cold before switching away.  Since
> hardware tends to be designed for the power on/off case more than for
> dynamic reconfiguration this should minimise pops and clicks during
> reconfiguration while active.
> Signed-off-by: Mark Brown <broonie at opensource.wolfsonmicro.com>
> ---
> Peter, I think this will address your widget reordering issue - I'd
> appreciate it if you could test and let me know if it helps.  If this
> works it avoids the need for the the widget to know anything about the
> particular algorithm implemented by DAPM which seems more robust to me.
> Sorry about how long it took to get this done.

Well, it is good, and bad.
It behaves mostly OK, but there's a strange side effect:
I noticed a pop on playback stream start on the twl4030 codec.
I'll look into it, but I do not see how this patch can affect the stream start..
Could you hold this patch for some time, so I can look at this?


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