[alsa-devel] [PATCH 3/3] ALSA: ASoC: cs4271: add optional soft reset workaround

[Daniel Mack]

On 02.12.2012 05:02, Mark Brown wrote:
> On Fri, Nov 30, 2012 at 11:28:57AM +0100, Daniel Mack wrote:
> 
>> +	Note that this is not needed in case the clocks are stable
>> +	throughout the entire runtime of the codec.
> 
> That's really quite rare for embeded systems, though - normally at least
> the LRCLK is going to be enabled only when there's audio. 

I agree, but I don't know which system the original driver was written
for. As it seems to work there, I didn't want to unconditionally
introduce this new reset command.

>> +static int cs4271_startup(struct snd_pcm_substream *subs,
>> +			   struct snd_soc_dai *codec_dai)
>> +{
>> +	int ret;
>> +	struct snd_soc_codec *codec = codec_dai->codec;
>> +	struct cs4271_private *cs4271 = snd_soc_codec_get_drvdata(codec);
>> +
>> +	if (!cs4271->enable_soft_reset)
>> +		return 0;
>> +
>> +	/*
>> +	 * Put the codec in soft reset and back again in case it's not
>> +	 * currently streaming data. This way of bringing the codec in
>> +	 * sync to the current clocks is not explicitly documented in
>> +	 * the data sheet, but it seems to work fine.
>> +	 */
> 
> Since startup() is called before hw_params() you might well find even an
> active LRCLK is going to change underneath the driver here...

Hmm ok, so you're saying this quirk should go in hwparams() then?



Thanks,
Daniel