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Date:   Mon, 22 Apr 2019 11:06:12 +0000
From:   Viorel Suman <viorel.suman@....com>
To:     Daniel Baluta <daniel.baluta@....com>,
        "broonie@...nel.org" <broonie@...nel.org>
CC:     dl-linux-imx <linux-imx@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "timur@...nel.org" <timur@...nel.org>,
        "Xiubo.Lee@...il.com" <Xiubo.Lee@...il.com>,
        "nicoleotsuka@...il.com" <nicoleotsuka@...il.com>,
        "festevam@...il.com" <festevam@...il.com>,
        "tiwai@...e.com" <tiwai@...e.com>,
        "lgirdwood@...il.com" <lgirdwood@...il.com>,
        "S.j. Wang" <shengjiu.wang@....com>,
        "perex@...ex.cz" <perex@...ex.cz>,
        "alsa-devel@...a-project.org" <alsa-devel@...a-project.org>
Subject: Re: [PATCH 3/3 v3] ASoC: fsl_sai: Move clock operation to PM runtime

Hi Daniel,

On Du, 2019-04-21 at 19:39 +0000, Daniel Baluta wrote:
> From: Shengjiu Wang <shengjiu.wang@....com>
> 
> Turn off/on clocks when device enters suspend/resume. This
> can help saving power.
> 
> As a further optimization, we turn off/on mclk only when SAI
> is in master mode because otherwise mclk is externally provided.
> 
> Signed-off-by: Shengjiu Wang <shengjiu.wang@....com>
> Signed-off-by: Daniel Baluta <daniel.baluta@....com>
> ---
>  sound/soc/fsl/fsl_sai.c | 60 ++++++++++++++++++++++++++++++++++-------
>  1 file changed, 50 insertions(+), 10 deletions(-)
> 
> diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
> index 8623b7f882b9..13a462360ed3 100644
> --- a/sound/soc/fsl/fsl_sai.c
> +++ b/sound/soc/fsl/fsl_sai.c
> @@ -596,15 +596,8 @@ static int fsl_sai_startup(struct snd_pcm_substream *substream,
>  {
>  	struct fsl_sai *sai = snd_soc_dai_get_drvdata(cpu_dai);
>  	bool tx = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
> -	struct device *dev = &sai->pdev->dev;
>  	int ret;
>  
> -	ret = clk_prepare_enable(sai->bus_clk);
> -	if (ret) {
> -		dev_err(dev, "failed to enable bus clock: %d\n", ret);
> -		return ret;
> -	}
> -
>  	regmap_update_bits(sai->regmap, FSL_SAI_xCR3(tx), FSL_SAI_CR3_TRCE,
>  			   FSL_SAI_CR3_TRCE);
>  
> @@ -621,8 +614,6 @@ static void fsl_sai_shutdown(struct snd_pcm_substream *substream,
>  	bool tx = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
>  
>  	regmap_update_bits(sai->regmap, FSL_SAI_xCR3(tx), FSL_SAI_CR3_TRCE, 0);
> -
> -	clk_disable_unprepare(sai->bus_clk);
>  }
>  
>  static const struct snd_soc_dai_ops fsl_sai_pcm_dai_ops = {
> @@ -932,6 +923,16 @@ static int fsl_sai_runtime_suspend(struct device *dev)
>  {
>  	struct fsl_sai *sai = dev_get_drvdata(dev);
>  
> +	if (!sai->is_slave_mode) {
This check is redundant as the bits in sai->mclk_streams are set/unset for master
mode only, please check fsl_sai_hw_params and fsl_sai_hw_free functions.

> +		if (sai->mclk_streams & BIT(SNDRV_PCM_STREAM_CAPTURE))
> +			clk_disable_unprepare(sai->mclk_clk[sai->mclk_id[0]]);
> +
> +		if (sai->mclk_streams & BIT(SNDRV_PCM_STREAM_PLAYBACK))
> +			clk_disable_unprepare(sai->mclk_clk[sai->mclk_id[1]]);
> +	}
> +
> +	clk_disable_unprepare(sai->bus_clk);
> +
>  	regcache_cache_only(sai->regmap, true);
>  	regcache_mark_dirty(sai->regmap);
>  
> @@ -941,6 +942,27 @@ static int fsl_sai_runtime_suspend(struct device *dev)
>  static int fsl_sai_runtime_resume(struct device *dev)
>  {
>  	struct fsl_sai *sai = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = clk_prepare_enable(sai->bus_clk);
> +	if (ret) {
> +		dev_err(dev, "failed to enable bus clock: %d\n", ret);
> +		return ret;
> +	}
> +
> +	if (!sai->is_slave_mode) {
> +		if (sai->mclk_streams & BIT(SNDRV_PCM_STREAM_PLAYBACK)) {
> +			ret = clk_prepare_enable(sai->mclk_clk[sai->mclk_id[1]]);
> +			if (ret)
> +				goto disable_bus_clk;
> +		}
> +
> +		if (sai->mclk_streams & BIT(SNDRV_PCM_STREAM_CAPTURE)) {
> +			ret = clk_prepare_enable(sai->mclk_clk[sai->mclk_id[0]]);
> +			if (ret)
> +				goto disable_tx_clk;
> +		}
> +	}
>  
>  	regcache_cache_only(sai->regmap, false);
>  	regmap_write(sai->regmap, FSL_SAI_TCSR, FSL_SAI_CSR_SR);
> @@ -948,7 +970,25 @@ static int fsl_sai_runtime_resume(struct device *dev)
>  	usleep_range(1000, 2000);
>  	regmap_write(sai->regmap, FSL_SAI_TCSR, 0);
>  	regmap_write(sai->regmap, FSL_SAI_RCSR, 0);
> -	return regcache_sync(sai->regmap);
> +
> +	ret = regcache_sync(sai->regmap);
> +	if (ret)
> +		goto disable_rx_clk;
> +
> +	return 0;
> +
> +disable_rx_clk:
> +	if (!sai->is_slave_mode &&
> +	    (sai->mclk_streams & BIT(SNDRV_PCM_STREAM_CAPTURE)))
> +		clk_disable_unprepare(sai->mclk_clk[sai->mclk_id[0]]);
> +disable_tx_clk:
> +	if (!sai->is_slave_mode &&
> +	    (sai->mclk_streams & BIT(SNDRV_PCM_STREAM_PLAYBACK)))
> +		clk_disable_unprepare(sai->mclk_clk[sai->mclk_id[1]]);
> +disable_bus_clk:
> +	clk_disable_unprepare(sai->bus_clk);
> +
> +	return ret;
>  }
>  #endif /* CONFIG_PM */
>  
> -- 
> 2.17.1
> 

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