linux-kernel - Re: [alsa-devel] [PATCH] ASoC: wm8994: Manage wm8994's MCLK in codec driver

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Message-id: <5501172D.2080804@samsung.com>
Date:	Thu, 12 Mar 2015 13:33:49 +0900
From:	Chanwoo Choi <cw00.choi@...sung.com>
To:	Inha Song <ideal.song@...sung.com>
Cc:	broonie@...nel.org, alsa-devel@...a-project.org,
	patches@...nsource.wolfsonmicro.com, linux-kernel@...r.kernel.org,
	ckeepax@...nsource.wolfsonmicro.com,
	nikesh@...nsource.wolfsonmicro.com, lars@...afoo.de,
	lgirdwood@...il.com, perex@...ex.cz, tiwai@...e.de,
	Li.Xiubo@...escale.com, sachin.kamat@...sung.com
Subject: Re: [alsa-devel] [PATCH] ASoC: wm8994: Manage wm8994's MCLK in codec
 driver

Hi Inha,

On 03/12/2015 11:49 AM, Inha Song wrote:
> Previously, When we use wm8994 codec, we should control its MCLK in machine driver.
> But, It should be managed by wm8994 codec driver, not machine driver.
> 
> This patch add MCLK clock DT parsing logic and control own MCLK.
> 
> Signed-off-by: Inha Song <ideal.song@...sung.com>
> ---
>  sound/soc/codecs/wm8994.c | 27 ++++++++++++++++++++++++++-
>  sound/soc/codecs/wm8994.h |  1 +
>  2 files changed, 27 insertions(+), 1 deletion(-)
> 
> diff --git a/sound/soc/codecs/wm8994.c b/sound/soc/codecs/wm8994.c
> index 247b390..d80dcc6 100644
> --- a/sound/soc/codecs/wm8994.c
> +++ b/sound/soc/codecs/wm8994.c
> @@ -16,6 +16,7 @@
>  #include <linux/init.h>
>  #include <linux/delay.h>
>  #include <linux/pm.h>
> +#include <linux/clk.h>
>  #include <linux/gcd.h>
>  #include <linux/i2c.h>
>  #include <linux/platform_device.h>
> @@ -2470,6 +2471,7 @@ static int wm8994_set_bias_level(struct snd_soc_codec *codec,
>  {
>  	struct wm8994_priv *wm8994 = snd_soc_codec_get_drvdata(codec);
>  	struct wm8994 *control = wm8994->wm8994;
> +	int i;
>  
>  	wm_hubs_set_bias_level(codec, level);
>  
> @@ -2491,8 +2493,19 @@ static int wm8994_set_bias_level(struct snd_soc_codec *codec,
>  			break;
>  		}
>  
> -		if (codec->dapm.bias_level == SND_SOC_BIAS_STANDBY)
> +		if (codec->dapm.bias_level == SND_SOC_BIAS_STANDBY) {
> +			for (i = 0; i < ARRAY_SIZE(wm8994->clk_mclk); i++) {
> +				if (!IS_ERR(wm8994->clk_mclk[i]))
> +					clk_prepare_enable(wm8994->clk_mclk[i]);

I think that you don't need to check error by using 'if' statement.
clk_prepare_enable() function will check the NULL state of clk instance
before preparing and enabling the clock. 

			for (i = 0; i < ARRAY_SIZE(wm8994->clk_mclk); i++)
				clk_prepare_enable(wm8994->clk_mclk[i]);

But, wm8994_probe() have to initialize the NULL for wm8994->clk_mclk[i].
I added the comment about this on below.

> +			}
>  			active_reference(codec);
> +		} else if (codec->dapm.bias_level == SND_SOC_BIAS_ON) {
> +			for (i = 0; i < ARRAY_SIZE(wm8994->clk_mclk); i++) {
> +				if (!IS_ERR(wm8994->clk_mclk[i]))
> +					clk_disable_unprepare(
> +							wm8994->clk_mclk[i]);
> +			}
> +		}
>  		break;
>  
>  	case SND_SOC_BIAS_STANDBY:
> @@ -4451,6 +4464,7 @@ static struct snd_soc_codec_driver soc_codec_dev_wm8994 = {
>  static int wm8994_probe(struct platform_device *pdev)
>  {
>  	struct wm8994_priv *wm8994;
> +	int i;
>  
>  	wm8994 = devm_kzalloc(&pdev->dev, sizeof(struct wm8994_priv),
>  			      GFP_KERNEL);
> @@ -4460,6 +4474,17 @@ static int wm8994_probe(struct platform_device *pdev)
>  
>  	wm8994->wm8994 = dev_get_drvdata(pdev->dev.parent);
>  
> +	for (i = 0; i < ARRAY_SIZE(wm8994->clk_mclk); i++) {
> +		char mclk_name[] = "MCLKx";
> +
> +		snprintf(mclk_name, sizeof(mclk_name), "MCLK%d", i + 1);
> +
> +		wm8994->clk_mclk[i] = devm_clk_get(pdev->dev.parent, mclk_name);
> +		if (IS_ERR(wm8994->clk_mclk[i]))
> +			if (PTR_ERR(wm8994->clk_mclk) == -EPROBE_DEFER)
> +				return -EPROBE_DEFER;

I think you better to modify exception handling as following:

		if (IS_ERR(wm8994->clk_mclk[i])) {
			wm8994->clk_mclk[i] = NULL;
			return PTR_ERR(wm8994->clk_mclk);
		}

> +	}
> +
>  	pm_runtime_enable(&pdev->dev);
>  	pm_runtime_idle(&pdev->dev);
>  
> diff --git a/sound/soc/codecs/wm8994.h b/sound/soc/codecs/wm8994.h
> index 6536f8d..8cf06a4 100644
> --- a/sound/soc/codecs/wm8994.h
> +++ b/sound/soc/codecs/wm8994.h
> @@ -78,6 +78,7 @@ struct wm8994_priv {
>  	int sysclk[2];
>  	int sysclk_rate[2];
>  	int mclk[2];
> +	struct clk *clk_mclk[2];
>  	int aifclk[2];
>  	int aifdiv[2];
>  	int channels[2];
> 

Thanks,
Chanwoo Choi
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