linux-kernel - Re: [alsa-devel] [PATCH 2/4] ASoC: da7213: Improve driver efficiency with regards to MCLK usage

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Date:	Mon, 8 Aug 2016 09:43:13 +0200 (CEST)
From:	Peter Meerwald-Stadler <pmeerw@...erw.net>
To:	Adam Thomson <Adam.Thomson.Opensource@...semi.com>
cc:	Mark Brown <broonie@...nel.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	Jaroslav Kysela <perex@...ex.cz>,
	Takashi Iwai <tiwai@...e.com>, alsa-devel@...a-project.org,
	Support Opensource <support.opensource@...semi.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [alsa-devel] [PATCH 2/4] ASoC: da7213: Improve driver efficiency
 with regards to MCLK usage


> Currently MCLK remains enabled during bias STANDBY state, and this
> is not necessary. This patch updates the code to handle enabling
> and disabling of MCLK, if provided, when moving between STANDBY
> and PREPARE states, therefore saving power when no active streams
> present.
> 
> Signed-off-by: Adam Thomson <Adam.Thomson.Opensource@...semi.com>

Tested-by: Peter Meerwald-Stadler <pmeerw@...erw.net>

> ---
>  sound/soc/codecs/da7213.c | 20 +++++++++++---------
>  1 file changed, 11 insertions(+), 9 deletions(-)
> 
> diff --git a/sound/soc/codecs/da7213.c b/sound/soc/codecs/da7213.c
> index bcf1834..7701f4e 100644
> --- a/sound/soc/codecs/da7213.c
> +++ b/sound/soc/codecs/da7213.c
> @@ -1454,11 +1454,10 @@ static int da7213_set_bias_level(struct snd_soc_codec *codec,
>  
>  	switch (level) {
>  	case SND_SOC_BIAS_ON:
> -	case SND_SOC_BIAS_PREPARE:
>  		break;
> -	case SND_SOC_BIAS_STANDBY:
> -		if (snd_soc_codec_get_bias_level(codec) == SND_SOC_BIAS_OFF) {
> -			/* MCLK */
> +	case SND_SOC_BIAS_PREPARE:
> +		/* Enable MCLK for transition to ON state */
> +		if (snd_soc_codec_get_bias_level(codec) == SND_SOC_BIAS_STANDBY) {
>  			if (da7213->mclk) {
>  				ret = clk_prepare_enable(da7213->mclk);
>  				if (ret) {
> @@ -1467,21 +1466,24 @@ static int da7213_set_bias_level(struct snd_soc_codec *codec,
>  					return ret;
>  				}
>  			}
> -
> +		}
> +		break;
> +	case SND_SOC_BIAS_STANDBY:
> +		if (snd_soc_codec_get_bias_level(codec) == SND_SOC_BIAS_OFF) {
>  			/* Enable VMID reference & master bias */
>  			snd_soc_update_bits(codec, DA7213_REFERENCES,
>  					    DA7213_VMID_EN | DA7213_BIAS_EN,
>  					    DA7213_VMID_EN | DA7213_BIAS_EN);
> +		} else {
> +			/* Remove MCLK */
> +			if (da7213->mclk)
> +				clk_disable_unprepare(da7213->mclk);
>  		}
>  		break;
>  	case SND_SOC_BIAS_OFF:
>  		/* Disable VMID reference & master bias */
>  		snd_soc_update_bits(codec, DA7213_REFERENCES,
>  				    DA7213_VMID_EN | DA7213_BIAS_EN, 0);
> -
> -		/* MCLK */
> -		if (da7213->mclk)
> -			clk_disable_unprepare(da7213->mclk);
>  		break;
>  	}
>  	return 0;
> 

-- 

Peter Meerwald-Stadler
+43-664-2444418 (mobile)