[alsa-devel] [PATCH 04/11] ASoC: rt5651: Simplify set_bias_level()

[Mark Brown]

On Wed, Feb 21, 2018 at 09:11:34PM +0100, Hans de Goede wrote:
> On 21-02-18 12:43, Mark Brown wrote:
> > On Tue, Feb 20, 2018 at 11:15:04PM +0100, Hans de Goede wrote:
> > > There is no need to set the LDO voltage to 1.2 volt each time we enter
> > > standby, instead always leave it 1.2 volt on BIAS_OFF. Note we do a
> > > snd_soc_codec_force_bias_level(BIAS_OFF) on probe, so this will configure
> > > it correctly right from the start.

> > That force on probe sounds like a problem...  if this is being done once
> > at startup it should be done in the probe function, not in the bias
> > level configuration.

> This is more like "we do a snd_soc_codec_force_bias_level(BIAS_OFF)
> on probe anyways and that already sets the level to 1.2 volt, so
> we don't need to do this explicitly at probe time".

What I'm saying is that if the code is written such that you need to do
that _force_bias_level() then it's not very idiomatic which is a bit
worrying - it might be safer to reorganize the code so that this isn't
required any more.

> > Also, are you sure this is a good fix?  If the bias voltage is being
> > configured all the time does that perhaps indicate that for better
> > performance or something it should have been being set to some other
> > voltage when the device is in standby?

> We switch the LDO off when in the bias level is BIAS_OFF and on
> at 1.2 volt when in standby or higher. Before this commit we would

OK.
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