Re: [alsa-devel] [PATCH] ASoC: Intel: bxt: Refine the HW contraint of Ref capture.

[Vinod Koul]

On Wed, Dec 06, 2017 at 03:21:27AM +0800, Harry Pan wrote:
> The patch restricts the HW contraint of the refcap of WoV stream
> in single channel (mono) and 16k Hz based on platform implementation.
> 
> Such that, the userspace program can rely on correct HW parameters
> through the ALSA library call to manipulate the device.

I think this has been discussed earlier in the context of kbl machine and we
dont want kernel to have such restrictions. User space can request and open
a mono stream..

> 
> Signed-off-by: Harry Pan <harry.pan@xxxxxxxxx>
> ---
>  sound/soc/intel/boards/bxt_da7219_max98357a.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/sound/soc/intel/boards/bxt_da7219_max98357a.c b/sound/soc/intel/boards/bxt_da7219_max98357a.c
> index ce35ec7884d1..382f71228807 100644
> --- a/sound/soc/intel/boards/bxt_da7219_max98357a.c
> +++ b/sound/soc/intel/boards/bxt_da7219_max98357a.c
> @@ -338,8 +338,23 @@ static const struct snd_pcm_hw_constraint_list constraints_16000 = {
>  	.list  = rates_16000,
>  };
>  
> +static const unsigned int ch_mono[] = {
> +	1,
> +};
> +
> +static const struct snd_pcm_hw_constraint_list constraints_refcap = {
> +	.count = ARRAY_SIZE(ch_mono),
> +	.list  = ch_mono,
> +};
> +
>  static int broxton_refcap_startup(struct snd_pcm_substream *substream)
>  {
> +	substream->runtime->hw.channels_max = 1;
> +
> +	snd_pcm_hw_constraint_list(substream->runtime, 0,
> +					SNDRV_PCM_HW_PARAM_CHANNELS,
> +					&constraints_refcap);
> +
>  	return snd_pcm_hw_constraint_list(substream->runtime, 0,
>  			SNDRV_PCM_HW_PARAM_RATE,
>  			&constraints_16000);
> -- 
> 2.13.5
> 
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-- 
~Vinod