[alsa-devel] [PATCH 2/5] ASoC: Add ADAU1361/ADAU1761 audio CODEC support

Mark Brown broonie at kernel.org
Thu Aug 29 11:53:56 CEST 2013

On Thu, Aug 29, 2013 at 10:02:47AM +0200, Lars-Peter Clausen wrote:
> On 08/28/2013 07:24 PM, Mark Brown wrote:

> > Not a requirement and perhaps it has no effect but these seem like they
> > ought to integrate with the bias level configuration - since only the
> > clocks seem to be managed by set_bias_level() the driver could
> > presumably save a bit of power by dropping down to the minimal power
> > consumption bias while the device is idle.  This is what the STANDBY to
> > ON transition is all about.

> Hm, I'm not sure if it makes a difference since all the components have
> individual power control bits that are managed by DAPM. I would expect the
> bias current setting to only make a difference if the component is actually
> powered up. I'll check with the designers, but I think this can still be
> improved later on if it turns out that it saves power.

Given that the device has non-capless headphone outputs I'd expect
there's something being maintained normally, though it's possible that
it's still ground referenced.

> >> +static const struct snd_kcontrol_new adau1761_jack_detect_controls[] = {
> >> +	SOC_SINGLE("Jack Detect Switch", ADAU1761_DIGMIC_JACKDETECT, 4, 1, 0),
> >> +};

> > Why is this a user visible control and not using the jack detection
> > framework support?

> The CODEC unfortunately does not support reporting the jack state. All it
> can do is mute the speaker output in hardware if something is plugged into
> the headphone jack. The switch allows the users to control whether the
> output should be auto-muted or not.

In that case it should be called something like "Speaker Automute
Switch" or similar.  It's a bit unfortuante that there's not even any
readback for the function.
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