[alsa-devel] [PATCH] ASoC: twl6040 - Add method to query optimum PDM_DL1 gain

[Liam Girdwood]

On Tue, 2012-01-10 at 00:44 +0000, Mark Brown wrote:
> On Mon, Jan 09, 2012 at 12:11:22PM +0000, Liam Girdwood wrote:
> > The DL1 PDM interface adds a little gain depending on the output device.
> > Add a method to retrieve the gain value for machine driver usage.
> 
> I'm having a hard time understanding how the machine driver would use
> this information...
> 

It's intended that the machine driver would use this information to
configure the ABE to compensate any attenuation so that the output
volume level was constant.

> > +int twl6040_get_dl1_gain(struct snd_soc_codec *codec)
> > +{
> > +	struct snd_soc_dapm_context *dapm = &codec->dapm;
> > +
> > +	if (snd_soc_dapm_get_pin_status(dapm, "EP"))
> > +		return -1; /* -1dB */
> 
> Shouldn't this be being done by reading the CODEC register settings to
> know which output DL1 is connected to?

The DL1 path output devices can all operate at the same time and may or
may not be connected by the machine drivers.

Liam