linux-kernel - Re: [PATCH 1/2] ASoC: max98090: Add master clock handling

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Message-ID: <CAHbNUh2QHv8n7Y19qfO7BagX5AWe0i17MjDvr7yOpHf6YNGW4A@mail.gmail.com>
Date:	Fri, 23 May 2014 11:05:17 +0530
From:	Tushar Behera <tushar.behera@...aro.org>
To:	Mark Brown <broonie@...nel.org>
Cc:	Linux-ALSA <alsa-devel@...a-project.org>,
	lkml <linux-kernel@...r.kernel.org>,
	devicetree <devicetree@...r.kernel.org>,
	Takashi Iwai <tiwai@...e.de>, Jaroslav Kysela <perex@...ex.cz>,
	Doug Anderson <dianders@...omium.org>,
	"jerry.wong" <jerry.wong@...imintegrated.com>
Subject: Re: [PATCH 1/2] ASoC: max98090: Add master clock handling

On 22 May 2014 16:00, Mark Brown <broonie@...nel.org> wrote:
> On Thu, May 22, 2014 at 02:47:07PM +0530, Tushar Behera wrote:
>
>> +     max98090->mclk = devm_clk_get(codec->dev, "mclk");
>> +     if (!IS_ERR(max98090->mclk))
>> +             clk_prepare_enable(max98090->mclk);
>> +
>
> Ths doesn't handle deferred probe, we need to at least return an error
> if we get -EPROBE_DEFER.
>

Ok.

> It'd also be better to move the enabling to set_bias_level() if possible
> (I don't know if the clock is needed for register access) though less
> essential.

I tested with moving clk_enable/clk_disable calls to set_bias_level():
SND_SOC_BIAS_PREPARE. That works well for me. Does it look okay?

@@ -1801,6 +1801,25 @@ static int max98090_set_bias_level(struct
snd_soc_codec *codec,
                break;

        case SND_SOC_BIAS_PREPARE:
+               /*
+                * SND_SOC_BIAS_PREPARE is called while preparing for a
+                * transition to ON or away from ON. If current bias_level
+                * is SND_SOC_BIAS_ON, then it is preparing for a transition
+                * away from ON. Disable the clock in that case, otherwise
+                * enable it.
+                */
+               if (!IS_ERR(max98090->mclk)) {
+                       if (codec->dapm.bias_level == SND_SOC_BIAS_ON)
+                               clk_disable(max98090->mclk);
+                       else
+                               clk_enable(max98090->mclk);
+               }
                break;

-- 
Tushar Behera
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