Re: [PATCH v2 2/2] ASoC: cs43130: Mute the PCM path from hw_free() to prepare()

[Charles Keepax <ckeepax@opensource.cirrus.com>]

On Fri, Oct 23, 2026 at 10:29:41PM +0200, Olivier Louvignes wrote:
> The PCM path is unmuted when DAPM powers it up and muted again only when
> DAPM powers it down, pmdown_time after the stream closes. Meanwhile the
> DAC plays whatever its serial port carries: on a HiBy R1 (CS43131 on an
> Ingenic X1600 I2S controller), loud white noise while a stream is open
> but stopped, as when paused, and until DAPM powers down after it closes.
> 
> Add a mute_stream() op, so that ASoC mutes the path at hw_free() and
> unmutes it at prepare(). The op is not run at trigger time, since the
> codec sits on I2C.
> 
> Signed-off-by: Olivier Louvignes <olivier@mgcrea.io>
> ---
> Changes in v2: rebased on broonie/sound for-next, the ops now sit next to
> .auto_selectable_formats. No other change.
> 
> Tested on v7.3 on a HiBy R1 (CS43131), by ear: no hiss while paused or
> after the stream stops. Build-tested with W=1 on for-next.
> 
>  sound/soc/codecs/cs43130.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/sound/soc/codecs/cs43130.c b/sound/soc/codecs/cs43130.c
> index 7fb23522f081..919280711f8d 100644
> --- a/sound/soc/codecs/cs43130.c
> +++ b/sound/soc/codecs/cs43130.c
> @@ -1624,6 +1624,20 @@ static int cs43130_set_sysclk(struct snd_soc_dai *codec_dai,
>  	return 0;
>  }
>  
> +/*
> + * Mutes the PCM path from hw_free() to the next prepare(). Otherwise it stays
> + * unmuted until DAPM powers it down, pmdown_time after the stream closes, and
> + * plays what the serial port carries meanwhile: white noise on the HiBy R1.
> + */
> +static int cs43130_mute_stream(struct snd_soc_dai *dai, int mute, int stream)
> +{
> +	struct snd_soc_component *component = dai->component;
> +	struct cs43130_private *cs43130 = snd_soc_component_get_drvdata(component);
> +
> +	return regmap_update_bits(cs43130->regmap, CS43130_PCM_PATH_CTL_1,
> +				  CS43130_MUTE_MASK, mute ? CS43130_MUTE_EN : 0);
> +}

I am slightly concerned about some variants of the chips
running additional register sequences around the mute, I
was not involved in the work on this driver so little unsure
how critical those are. Would it perhaps be slightly safer to
just remove use_pmdown_time? Thereby forcing the chip to
power down immediately.

Thanks,
Charles

> +
>  static const u64 cs43130_selectable_formats =
>  	SND_SOC_POSSIBLE_DAIFMT_I2S	|
>  	SND_SOC_POSSIBLE_DAIFMT_LEFT_J	|
> @@ -1640,6 +1654,8 @@ static const struct snd_soc_dai_ops cs43130_pcm_ops = {
>  	.hw_free	= cs43130_hw_free,
>  	.set_sysclk	= cs43130_set_sysclk,
>  	.set_fmt	= cs43130_pcm_set_fmt,
> +	.mute_stream	= cs43130_mute_stream,
> +	.no_capture_mute = 1,
>  	.auto_selectable_formats	= &cs43130_selectable_formats,
>  	.num_auto_selectable_formats	= 1,
>  };
> -- 
> 2.39.5
>