[alsa-devel] [PATCH 3/3] ALSA: ASoC: cs4271: add optional soft reset workaround
broonie at opensource.wolfsonmicro.com
Sun Dec 2 05:02:01 CET 2012
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.
> +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...
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