[alsa-devel] [PATCH] ASoC: codecs: dmic: Make number of channels configurable

[Arnaud Pouliquen]

Hello Mathias,

Next time could you add patch version in your mail subject ( [PATCH vX])
easier to follow versions :-).

otherwise,

Acked-by: Arnaud Pouliquen <arnaud.pouliquen at st.com>

Regards,
Arnaud

On 01/05/2018 09:39 PM, Matthias Kaehlcke wrote:
> The DMIC DAI driver specifies a number of 1 to 8 channels for each DAI.
> The actual number of mics can currently not be configured in the device
> tree or audio glue, but is derived from the min/max channels of the CPU
> and codec DAI. A typical CPU DAI has two or more channels, in consequence
> a single mic is treated as a stereo/multi channel device, even though
> only one channel carries audio data.
> 
> This change adds the option to specify the number of used DMIC channels
> in the device tree. When specified this value overwrites the default
> channels_max value of 8 in the snd_soc_dai_driver struct of the codec.
> 
> Signed-off-by: Matthias Kaehlcke <mka at chromium.org>
> ---
>  Documentation/devicetree/bindings/sound/dmic.txt |  2 ++
>  sound/soc/codecs/dmic.c                          | 24
> +++++++++++++++++++++++-
>  2 files changed, 25 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/sound/dmic.txt
> b/Documentation/devicetree/bindings/sound/dmic.txt
> index 54c8ef6498a8..f7bf65611453 100644
> --- a/Documentation/devicetree/bindings/sound/dmic.txt
> +++ b/Documentation/devicetree/bindings/sound/dmic.txt
> @@ -7,10 +7,12 @@ Required properties:
>  
>  Optional properties:
>          - dmicen-gpios: GPIO specifier for dmic to control start and stop
> +       - num-channels: Number of microphones on this DAI
>  
>  Example node:
>  
>          dmic_codec: dmic at 0 {
>                  compatible = "dmic-codec";
>                  dmicen-gpios = <&gpio4 3 GPIO_ACTIVE_HIGH>;
> +               num-channels = <1>;
>          };
> diff --git a/sound/soc/codecs/dmic.c b/sound/soc/codecs/dmic.c
> index b88a1ee66f80..c88f974ebe3e 100644
> --- a/sound/soc/codecs/dmic.c
> +++ b/sound/soc/codecs/dmic.c
> @@ -107,8 +107,30 @@ static const struct snd_soc_codec_driver soc_dmic = {
>  
>  static int dmic_dev_probe(struct platform_device *pdev)
>  {
> +       int err;
> +       u32 chans;
> +       struct snd_soc_dai_driver *dai_drv = &dmic_dai;
> +
> +       if (pdev->dev.of_node) {
> +               err = of_property_read_u32(pdev->dev.of_node,
> "num-channels", &chans);
> +               if (err && (err != -ENOENT))
> +                       return err;
> +
> +               if (!err) {
> +                       if (chans < 1 || chans > 8)
> +                               return -EINVAL;
> +
> +                       dai_drv = devm_kzalloc(&pdev->dev,
> sizeof(*dai_drv), GFP_KERNEL);
> +                       if (!dai_drv)
> +                               return -ENOMEM;
> +
> +                       memcpy(dai_drv, &dmic_dai, sizeof(*dai_drv));
> +                       dai_drv->capture.channels_max = chans;
> +               }
> +       }
> +

>          return snd_soc_register_codec(&pdev->dev,
> -                       &soc_dmic, &dmic_dai, 1);
> +                       &soc_dmic, dai_drv, 1);
>  }
>  
>  static int dmic_dev_remove(struct platform_device *pdev)
> -- 
> 2.16.0.rc0.223.g4a4ac83678-goog
>