[alsa-devel] [patch 1/3] ASoC: add support for alc562[123] codecs

[Arnaud Patard (Rtp)]

Mark Brown <broonie at opensource.wolfsonmicro.com> writes:

> On Wed, Oct 13, 2010 at 07:58:03PM +0200, Arnaud Patard wrote:
>> Mark Brown <broonie at opensource.wolfsonmicro.com> writes:
>
>> >> +	switch (level) {
>> >> +	case SND_SOC_BIAS_ON:
>> >> +		enable_power_depop(codec);
>> >> +		break;
>
>> > enable_power_depop() takes a rather long time - about 500ms - which is
>> > surprising for _ON.  Are you sure it should be done here?
>
>> It was there in the original driver and when working on this driver, I
>> didn't see any reason for moving it elsewhere. tbh, if I have to move it
>> elsewhere, I don't know where I'll put it.
>
> Normally _PREPARE if you must do it whenever bringing up playback but
> generally you should try to do anything really slow when bringing the
> biases up to standby.  Bear in mind that I've no idea what's actually
> being done here...

The power_depop stuff aims at avoiding "pop noise" in the output
according to the datasheet which iiuc happens when going from standby to
on.
Unfortunately, I can't give details because it's described in the codec
application note which I've been unable to find.

Arnaud