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

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Message-ID: <20140703151944.GS5814@saruman.home>
Date:	Thu, 3 Jul 2014 10:19:44 -0500
From:	Felipe Balbi <balbi@...com>
To:	Dan Murphy <dmurphy@...com>
CC:	<balbi@...com>, <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

On Thu, Jul 03, 2014 at 10:13:06AM -0500, Dan Murphy wrote:
> 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.

that'd be cool.

-- 
balbi

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