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

From: Takashi Iwai <tiwai@suse.de>
To: Brent Lu <brent.lu@intel.com>
Cc: alsa-devel@alsa-project.org, kuninori.morimoto.gx@renesas.com,
	yang.jie@linux.intel.com, cezary.rojewski@intel.com,
	pierre-louis.bossart@linux.intel.com,
	liam.r.girdwood@linux.intel.com, broonie@kernel.org,
	tglx@linutronix.de
Subject: Re: [alsa-devel] [PATCH] ASoC: bdw-rt5677: channel constraint support
Date: Thu, 12 Sep 2019 09:00:43 +0200	[thread overview]
Message-ID: <s5ha7ba3so4.wl-tiwai@suse.de> (raw)
In-Reply-To: <1567733058-9561-1-git-send-email-brent.lu@intel.com>

On Fri, 06 Sep 2019 03:24:18 +0200,
Brent Lu wrote:
> 
> BDW boards using this machine driver supports only stereo capture and
> playback. Implement a constraint to enforce it.
> 
> Signed-off-by: Brent Lu <brent.lu@intel.com>
> ---
>  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);

Can't we simply set both channels_min and channels_max to 2?

thanks,

Takashi

> +
> +	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),
>  	},
>  
> -- 
> 2.7.4
> 
> 
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