linux-kernel - Re: [PATCH v4] ASoC: tas2552: Support TI TAS2552 Amplifier

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Date:	Thu, 3 Jul 2014 10:13:06 -0500
From:	Dan Murphy <dmurphy@...com>
To:	<balbi@...com>
CC:	<linux-sound@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<alsa-devel@...a-project.org>, <broonie@...nel.org>,
	<devicetree@...r.kernel.org>
Subject: Re: [PATCH v4] ASoC: tas2552: Support TI TAS2552 Amplifier

Hi

On 07/03/2014 10:06 AM, Felipe Balbi wrote:
> Hi,
>
> On Thu, Jul 03, 2014 at 09:57:39AM -0500, Dan Murphy wrote:
>> On 07/03/2014 09:52 AM, Felipe Balbi wrote:
>>> Hi,
>>>
>>> On Thu, Jul 03, 2014 at 09:39:53AM -0500, Dan Murphy wrote:
>>>> +static int tas2552_set_dai_fmt(struct snd_soc_dai *dai, unsigned int fmt)
>>>> +{
>>>> +	u8 serial_format;
>>>> +	struct snd_soc_codec *codec = dai->codec;
>>>> +
>>>> +	switch (fmt & SND_SOC_DAIFMT_MASTER_MASK) {
>>>> +	case SND_SOC_DAIFMT_CBS_CFS:
>>>> +		serial_format = 0x00;
>>>> +		break;
>>>> +	case SND_SOC_DAIFMT_CBS_CFM:
>>>> +		serial_format = TAS2552_WORD_CLK_MASK;
>>>> +		break;
>>>> +	case SND_SOC_DAIFMT_CBM_CFS:
>>>> +		serial_format = TAS2552_BIT_CLK_MASK;
>>>> +		break;
>>>> +	case SND_SOC_DAIFMT_CBM_CFM:
>>>> +		serial_format = (TAS2552_BIT_CLK_MASK | TAS2552_WORD_CLK_MASK);
>>>> +		break;
>>>> +	default:
>>>> +		return -EINVAL;
>>>> +	}
>>>> +
>>>> +	pm_runtime_get_sync(codec->dev);
>>>> +
>>>> +	snd_soc_update_bits(codec, TAS2552_SER_CTRL_1,
>>>> +			    (TAS2552_BIT_CLK_MASK | TAS2552_WORD_CLK_MASK),
>>>> +			    serial_format);
>>>> +
>>>> +	pm_runtime_put(codec->dev);
>>> I have a feeling it's better to just put at the end of the function.
>>> Remember your pm_runtime_put() will issue i2c transfers which can take a
>>> looooooong time ;-)
>> I thought about that but the next switch case could return if the format
>> mask is invalid which means the runtime calls would not be balanced.
>>
>> So I decided to wrap the snd_soc calls with the pm_runtime calls to keep it
>> balanced.
> it looks like you can do both switch statements outside of the
> pm_runtime region and cache results on serial_format and do a single
> write to CTRL_1 register (?). If not, then just use two local variables.
>

Yeah I could probably consolidate these into a single call.  And throw a debug statement
in the default case to why the format was not set.

Dan

-- 
------------------
Dan Murphy

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