linux-kernel - RE: [alsa-devel] [PATCH] ASoC: bdw-rt5677: channel constraint support

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Date:   Mon, 9 Sep 2019 06:34:25 +0000
From:   "Lu, Brent" <brent.lu@...el.com>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        "alsa-devel@...a-project.org" <alsa-devel@...a-project.org>
CC:     "Rojewski, Cezary" <cezary.rojewski@...el.com>,
        "liam.r.girdwood@...ux.intel.com" <liam.r.girdwood@...ux.intel.com>,
        "yang.jie@...ux.intel.com" <yang.jie@...ux.intel.com>,
        "broonie@...nel.org" <broonie@...nel.org>,
        "perex@...ex.cz" <perex@...ex.cz>,
        "tiwai@...e.com" <tiwai@...e.com>,
        "kuninori.morimoto.gx@...esas.com" <kuninori.morimoto.gx@...esas.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [alsa-devel] [PATCH] ASoC: bdw-rt5677: channel constraint
 support

Hi Pierre

We are working on a backport 3.14 branch for Chrome projects based on BDW platform. In the branch 4-channel capture is supported on some platforms but not all. So we need to add a constraint in the machine driver for machines don't support this feature.

I checked the for-next branch in the broonie repo. The channels_max of HSW_PCM_DAI_ID_SYSTEM is 4 for capture stream so I think it would have same issue like google's backport tree. I didn't find any constraint for this dai. Would you point out where it is?

		.capture = {
			.stream_name = "Analog Capture",
			.channels_min = 2,
			.channels_max = 4,
			.rates = SNDRV_PCM_RATE_48000,
			.formats = SNDRV_PCM_FMTBIT_S24_LE | SNDRV_PCM_FMTBIT_S16_LE,
		},

Regards,
Brent Lu

-----Original Message-----
From: Pierre-Louis Bossart [mailto:pierre-louis.bossart@...ux.intel.com] 
Sent: Friday, September 6, 2019 10:21 PM
To: Lu, Brent <brent.lu@...el.com>; alsa-devel@...a-project.org
Cc: Rojewski, Cezary <cezary.rojewski@...el.com>; liam.r.girdwood@...ux.intel.com; yang.jie@...ux.intel.com; broonie@...nel.org; perex@...ex.cz; tiwai@...e.com; kuninori.morimoto.gx@...esas.com; tglx@...utronix.de; linux-kernel@...r.kernel.org
Subject: Re: [alsa-devel] [PATCH] ASoC: bdw-rt5677: channel constraint support

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@...el.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);
> +
> +	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),
>   	},
>   
>