[alsa-devel] How to apply a SOC_DAPM_MUX if two there are two different input register for left and right channel?

[Charles Keepax]

On Wed, Sep 06, 2017 at 03:35:36PM +0200, Oleksandr Müller wrote:
> Hello guys,
> 
> I have some trouble I want to implement a mux within the mixer application
> for the VIN source of my adc. Taking a look into the datasheet of the
> TI-PCM1863 adc I get the information that the VIN left register is at the
> 0x06 and the VIN right register is at the 0x07 address. Right now my code
> would look like this and here comes the problem it seems that there is only
> a SOC_ENUM_SINGLE_DECL or a SOC_ENUM_DOUBLE_DECL but no
> SOC_ENUM_DOUBLE_R_DECL because the DOUBLE_DECL only allows shiftl and shiftr
> as the input parameters but I would need a regl regr parameter. Is the only
> option to duplicate the code and define a VIN_L_MUX and a VIN_R_MUX?
> 
> static const char * const pcm1863_adc_vin_src[] = {
>         "VIN1", "VIN2", "VIN3", "VIN4"
> };
> 
> static SOC_ENUM_SINGLE_DECL(
>         pcm1863_adc_vin_enum, PCM1863_ADC1_INPUT_SEL_L,
>         PCM1863_SEL_L_SHIFT, pcm1863_vin_src);
> 
> static const struct snd_kcontrol_new pcm1863_adc_vin_mux =
>         SOC_DAPM_ENUM("ADC VIN Source", pcm1863_adc_vin_enum);
> 
> static const struct snd_soc_dapm_widget pcm1863_dapm_widgets[] = {
>         [...]
>         SND_SOC_DAPM_MUX("ADC VIN Mux", SND_SOC_NOPM, 0, 0,
>                                 &pcm1863_adc_vin_mux),
> };

Currently yes ASoC does not have support for Stereo muxes that
have a different register for both the left and right channel.
Your two options are add single muxes as you suggest or extend
the framework to support what you require. I would probably
suggest that it seems like something I can see existing in other
devices so extending the framework to support it is probably the
better option.

Thanks,
Charles