Re: [alsa-devel] [PATCH] ASoC: bdw-rt5677: channel constraint support

[Pierre-Louis Bossart]

On 9/5/19 8:24 PM, Brent Lu wrote:
> BDW boards using this machine driver supports only stereo capture and
> playback. Implement a constraint to enforce it.

Humm, can you clarify what problem/error this patch fixes?

There are already constraints on the hsw_dais[] where the channels are 
stereo only.

Thanks
-Pierre

> Signed-off-by: Brent Lu <brent.lu@xxxxxxxxx>
> ---
>   sound/soc/intel/boards/bdw-rt5677.c | 33 +++++++++++++++++++++++++++++++++
>   1 file changed, 33 insertions(+)
>
> diff --git a/sound/soc/intel/boards/bdw-rt5677.c b/sound/soc/intel/boards/bdw-rt5677.c
> index 4a4d335..a312b55 100644
> --- a/sound/soc/intel/boards/bdw-rt5677.c
> +++ b/sound/soc/intel/boards/bdw-rt5677.c
> @@ -22,6 +22,8 @@
>   
>   #include "../../codecs/rt5677.h"
>   
> +#define DUAL_CHANNEL 2
> +
>   struct bdw_rt5677_priv {
>   	struct gpio_desc *gpio_hp_en;
>   	struct snd_soc_component *component;
> @@ -245,6 +247,36 @@ static int bdw_rt5677_init(struct snd_soc_pcm_runtime *rtd)
>   	return 0;
>   }
>   
> +static const unsigned int channels[] = {
> +	DUAL_CHANNEL,
> +};
> +
> +static const struct snd_pcm_hw_constraint_list constraints_channels = {
> +	.count = ARRAY_SIZE(channels),
> +	.list = channels,
> +	.mask = 0,
> +};
> +
> +static int bdw_fe_startup(struct snd_pcm_substream *substream)
> +{
> +	struct snd_pcm_runtime *runtime = substream->runtime;
> +
> +	/*
> +	 * On this platform for PCM device we support,
> +	 * stereo
> +	 */
> +
> +	runtime->hw.channels_max = DUAL_CHANNEL;
> +	snd_pcm_hw_constraint_list(runtime, 0, SNDRV_PCM_HW_PARAM_CHANNELS,
> +					   &constraints_channels);
> +
> +	return 0;
> +}
> +
> +static const struct snd_soc_ops bdw_rt5677_fe_ops = {
> +	.startup = bdw_fe_startup,
> +};
> +
>   /* broadwell digital audio interface glue - connects codec <--> CPU */
>   SND_SOC_DAILINK_DEF(dummy,
>   	DAILINK_COMP_ARRAY(COMP_DUMMY()));
> @@ -273,6 +305,7 @@ static struct snd_soc_dai_link bdw_rt5677_dais[] = {
>   		},
>   		.dpcm_capture = 1,
>   		.dpcm_playback = 1,
> +		.ops = &bdw_rt5677_fe_ops,
>   		SND_SOC_DAILINK_REG(fe, dummy, platform),
>   	},
>