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

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Message-id: <20150312140218.716a0ac1@songinha-Samsung-DeskTop-System>
Date:	Thu, 12 Mar 2015 14:02:18 +0900
From:	Inha Song <ideal.song@...sung.com>
To:	Chanwoo Choi <cw00.choi@...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, Chanwoo,

Thanks for your comments.

On Thu, 12 Mar 2015 13:33:49 +0900
Chanwoo Choi <cw00.choi@...sung.com> wrote:

> 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. 

So that, I can handle it more concisely. Thanks, I will fix this.

> 
> 			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]);

ditto

> > +			}
> > +		}
> >  		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);

I will fix. (MCLK is optional properties in wm8994)

	if (IS_ERR(wm8994->clk_mclk[i]))
		wm8994->clk_mclk[i] = NULL;

Best Regards,
Inha Song.

> 		}
> 
> > +	}
> > +
> >  	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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