[alsa-devel] [PATCH v4 1/2] ASoC: core: allow DAI PCM controls bound to PCM device

[Takashi Sakamoto]

Hi,

On Nov 30 2016 19:24, Arnaud Pouliquen wrote:
> In case of several instances of the same PCM control (e.g IEC controls).
> Application should be able to address the control using the
> device field number, according to the PCM character device.
> This patch allows to link DAI PCM controls to the PCM device.
> During DAI_link probe, PCM controls are added after device field is forced
> to the PCM device number.
>
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen at st.com>
> ---
>  include/sound/soc-dai.h |  4 ++++
>  sound/soc/soc-core.c    | 35 +++++++++++++++++++++++++++++++++++
>  2 files changed, 39 insertions(+)
>
> diff --git a/include/sound/soc-dai.h b/include/sound/soc-dai.h
> index 200e1f0..3ff1a86 100644
> --- a/include/sound/soc-dai.h
> +++ b/include/sound/soc-dai.h
> @@ -273,6 +273,10 @@ struct snd_soc_dai_driver {
>  	/* probe ordering - for components with runtime dependencies */
>  	int probe_order;
>  	int remove_order;
> +
> +	/* Optional PCM controls to bind to PCM device on DAIs link*/

In this patchset, you newly request developers to pay enough attention 
to 'iface' field of identification information for the control element 
set. This is logically correct, however such kind of special requirement 
should be described in code comment for the other developers to start 
using this feature easily.

> +	const struct snd_kcontrol_new *pcm_controls;
> +	int num_pcm_controls;
>  };
>
>  /*
> diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
> index aaab26a..7b79a31 100644
> --- a/sound/soc/soc-core.c
> +++ b/sound/soc/soc-core.c
> @@ -1598,6 +1598,32 @@ static int soc_probe_dai(struct snd_soc_dai *dai, int order)
>  	return 0;
>  }
>
> +static int soc_link_dai_pcm_controls(struct snd_soc_dai **dais, int num_dais,
> +				     struct snd_soc_pcm_runtime *rtd)
> +{
> +	struct snd_kcontrol_new kctl;
> +	int i, j, ret;
> +
> +	for (i = 0; i < num_dais; ++i) {
> +		for (j = 0; j < dais[i]->driver->num_pcm_controls; j++) {
> +			kctl = dais[i]->driver->pcm_controls[j];
> +			if (kctl.iface != SNDRV_CTL_ELEM_IFACE_PCM ||
> +			    rtd->dai_link->no_pcm) {
> +				dev_err(dais[i]->dev,
> +					"Failed to bind control: %s\n",
> +					kctl.name);

It's better to output name of the DAI driver, to make it easy to 
identify which driver causes this issue, as well.

> +				return -EINVAL;
> +			}
> +			kctl.device = rtd->pcm->device;
> +			ret = snd_soc_add_dai_controls(dais[i], &kctl, 1);
> +			if (ret < 0)
> +				return ret;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
>  static int soc_link_dai_widgets(struct snd_soc_card *card,
>  				struct snd_soc_dai_link *dai_link,
>  				struct snd_soc_pcm_runtime *rtd)
> @@ -1709,6 +1735,15 @@ static int soc_probe_link_dais(struct snd_soc_card *card,
>  				       dai_link->stream_name, ret);
>  				return ret;
>  			}
> +
> +			/* Bind DAIs pcm controls to the PCM device */
> +			ret = soc_link_dai_pcm_controls(&cpu_dai, 1, rtd);
> +			if (ret < 0)
> +				return ret;
> +			ret = soc_link_dai_pcm_controls(rtd->codec_dais,
> +							rtd->num_codecs, rtd);
> +			if (ret < 0)
> +				return ret;
>  		} else {
>  			INIT_DELAYED_WORK(&rtd->delayed_work,
>  						codec2codec_close_delayed_work);

Regards

Takashi Sakamoto