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Subject: Re: [PATCH 2/3] ASoC: bdw-rt5650: channel constraint support
To:     Brent Lu <brent.lu@intel.com>, alsa-devel@alsa-project.org
Cc:     Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
        Liam Girdwood <liam.r.girdwood@linux.intel.com>,
        Jie Yang <yang.jie@linux.intel.com>,
        Mark Brown <broonie@kernel.org>,
        Jaroslav Kysela <perex@perex.cz>,
        Takashi Iwai <tiwai@suse.com>, Ben Zhang <benzh@chromium.org>,
        Mac Chiang <mac.chiang@intel.com>,
        Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>,
        Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>,
        linux-kernel@vger.kernel.org
References: <1587976638-29806-1-git-send-email-brent.lu@intel.com>
 <1587976638-29806-3-git-send-email-brent.lu@intel.com>
From:   Cezary Rojewski <cezary.rojewski@intel.com>
Message-ID: <dc30437d-440b-937b-910f-6876bbc7cf56@intel.com>
Date:   Mon, 27 Apr 2020 12:58:41 +0200
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On 2020-04-27 10:37, Brent Lu wrote:
> BDW boards using this machine driver supports only 2 or 4-channel capture.
> Implement a constraint to enforce it.
> 

What about playback configurations?

Title for the overall series fits better than the one chosen for actual 
patches. "channel constraint support" is misleading. Constraints are 
added or removed but certainly not supported.

> Signed-off-by: Brent Lu <brent.lu@intel.com>
> ---
>   sound/soc/intel/boards/bdw-rt5650.c | 34 ++++++++++++++++++++++++++++++++++
>   1 file changed, 34 insertions(+)
> 
> diff --git a/sound/soc/intel/boards/bdw-rt5650.c b/sound/soc/intel/boards/bdw-rt5650.c
> index af2f502..dd4f219 100644
> --- a/sound/soc/intel/boards/bdw-rt5650.c
> +++ b/sound/soc/intel/boards/bdw-rt5650.c
> @@ -21,6 +21,9 @@
>   
>   #include "../../codecs/rt5645.h"
>   
> +#define DUAL_CHANNEL 2
> +#define QUAD_CHANNEL 4
> +

Remove, we need not additional too-obvious macro. One could argue 
'STEREO' is a better choice for '2' channel configuration too.

>   struct bdw_rt5650_priv {
>   	struct gpio_desc *gpio_hp_en;
>   	struct snd_soc_component *component;
> @@ -162,6 +165,36 @@ static int bdw_rt5650_rtd_init(struct snd_soc_pcm_runtime *rtd)
>   }
>   #endif
>   
> +static const unsigned int channels[] = {
> +	DUAL_CHANNEL, QUAD_CHANNEL,

Inline as stated above.

> +};
> +
> +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)

Entire file uses 'bdw_rt5650_' naming convention. Let's not stray away 
from that path now.

> +{
> +	struct snd_pcm_runtime *runtime = substream->runtime;
> +

Missing hw.channels_max assignment from rt5677 - inconsistency/ copy error?

> +	/*
> +	 * On this platform for PCM device we support,
> +	 * 2 or 4 channel capture
> +	 */

Sometimes you add a newline add and before, while other times just one, 
before the comment. Please streamline the format across all patches in 
the series. Comment can be more strict too
	/* Board supports stereo and quad configurations */

> +	if (substream->stream == SNDRV_PCM_STREAM_CAPTURE)
> +		snd_pcm_hw_constraint_list(runtime, 0,
> +					   SNDRV_PCM_HW_PARAM_CHANNELS,
> +					   &constraints_channels);

Redesign to reduce indentation and improve readability -
	if (stream != capture)
		return 0;

	return snd_pcm_hw_contraint_list(...);

> +
> +	return 0;
> +}
> +
> +static const struct snd_soc_ops bdw_rt5650_fe_ops = {
> +	.startup = bdw_fe_startup,
> +};
> +
>   static int bdw_rt5650_init(struct snd_soc_pcm_runtime *rtd)
>   {
>   	struct bdw_rt5650_priv *bdw_rt5650 =
> @@ -234,6 +267,7 @@ static struct snd_soc_dai_link bdw_rt5650_dais[] = {
>   		.name = "System PCM",
>   		.stream_name = "System Playback",
>   		.dynamic = 1,
> +		.ops = &bdw_rt5650_fe_ops,
>   #if !IS_ENABLED(CONFIG_SND_SOC_SOF_BROADWELL)
>   		.init = bdw_rt5650_rtd_init,
>   #endif
>