linux-kernel - Re: [PATCH v2 4/5] ASoC: codecs: wcd938x: add mux control support for hp audio mux

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Message-ID: <3ke2oxgd2dh5wghgatyzivaxspqlezn3x5vtjaxszqad4dhfxd@vpzxmi2nqmrw>
Date: Fri, 21 Mar 2025 19:16:25 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Cc: peda@...ntia.se, broonie@...nel.org, andersson@...nel.org,
        krzk+dt@...nel.org, ivprusov@...utedevices.com,
        luca.ceresoli@...tlin.com, zhoubinbin@...ngson.cn,
        paulha@...nsource.cirrus.com, lgirdwood@...il.com, robh@...nel.org,
        conor+dt@...nel.org, konradybcio@...nel.org, perex@...ex.cz,
        tiwai@...e.com, linux-sound@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, johan+linaro@...nel.org
Subject: Re: [PATCH v2 4/5] ASoC: codecs: wcd938x: add mux control support
 for hp audio mux

On Fri, Mar 21, 2025 at 02:14:31PM +0000, Srinivas Kandagatla wrote:
> 
> 
> On 20/03/2025 14:03, Dmitry Baryshkov wrote:
> > On Thu, Mar 20, 2025 at 11:56:32AM +0000, srinivas.kandagatla@...aro.org wrote:
> > > From: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
> > > 
> > > On some platforms to minimise pop and click during switching between
> > > CTIA and OMTP headset an additional HiFi mux is used. Most common
> > > case is that this switch is switched on by default, but on some
> > > platforms this needs a regulator enable.
> > > 
> > > move to using mux control to enable both regulator and handle gpios,
> > > deprecate the usage of gpio.
> > > 
> > > Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
> > > ---
> > >   sound/soc/codecs/Kconfig   |  2 ++
> > >   sound/soc/codecs/wcd938x.c | 38 ++++++++++++++++++++++++++++++--------
> > >   2 files changed, 32 insertions(+), 8 deletions(-)
> > > 
> > > diff --git a/sound/soc/codecs/Kconfig b/sound/soc/codecs/Kconfig
> > > index ee35f3aa5521..b04076282c8b 100644
> > > --- a/sound/soc/codecs/Kconfig
> > > +++ b/sound/soc/codecs/Kconfig
> > > @@ -2226,6 +2226,8 @@ config SND_SOC_WCD938X
> > >   	tristate
> > >   	depends on SOUNDWIRE || !SOUNDWIRE
> > >   	select SND_SOC_WCD_CLASSH
> > > +	select MULTIPLEXER
> > > +	imply MUX_GPIO
> > 
> > Why? This is true for a particular platform, isn't it?
> > 
> > >   config SND_SOC_WCD938X_SDW
> > >   	tristate "WCD9380/WCD9385 Codec - SDW"
> > > diff --git a/sound/soc/codecs/wcd938x.c b/sound/soc/codecs/wcd938x.c
> > > index f2a4f3262bdb..b7a235eef6ba 100644
> > > --- a/sound/soc/codecs/wcd938x.c
> > > +++ b/sound/soc/codecs/wcd938x.c
> > > @@ -19,6 +19,7 @@
> > >   #include <linux/regmap.h>
> > >   #include <sound/soc.h>
> > >   #include <sound/soc-dapm.h>
> > > +#include <linux/mux/consumer.h>
> > >   #include <linux/regulator/consumer.h>
> > >   #include "wcd-clsh-v2.h"
> > > @@ -178,6 +179,8 @@ struct wcd938x_priv {
> > >   	int variant;
> > >   	int reset_gpio;
> > >   	struct gpio_desc *us_euro_gpio;
> > > +	struct mux_control *us_euro_mux;
> > > +	u32 mux_state;
> > >   	u32 micb1_mv;
> > >   	u32 micb2_mv;
> > >   	u32 micb3_mv;
> > > @@ -3243,9 +3246,16 @@ static bool wcd938x_swap_gnd_mic(struct snd_soc_component *component, bool activ
> > >   	wcd938x = snd_soc_component_get_drvdata(component);
> > > -	value = gpiod_get_value(wcd938x->us_euro_gpio);
> > > +	if (!wcd938x->us_euro_mux) {
> > > +		value = gpiod_get_value(wcd938x->us_euro_gpio);
> > > -	gpiod_set_value(wcd938x->us_euro_gpio, !value);
> > > +		gpiod_set_value(wcd938x->us_euro_gpio, !value);
> > 
> > This looks like a separate topic, but why is 'active' being ignored?
> > 
> > > +	} else {
> > > +		mux_control_deselect(wcd938x->us_euro_mux);
> > > +		wcd938x->mux_state = !wcd938x->mux_state;
> > > +		if (mux_control_select(wcd938x->us_euro_mux, wcd938x->mux_state))
> > 
> > Can't it just be 'mux_control_select(wcd938x->us_euro_mux, active)' ?
> > 
> 
> No, the way this is supposed to work is that if the codec detects cross
> connection, It will try to switch the mux to other option.

I see. It would be nice then to converge GPIO code and mux code in this
area. Invert mux_state, then use it in both paths.
> 
> So using active will just work if we try to pulg one type of headset all the
> time. But if we change the headset type the mux will still be configured to
> use the old headset type and not work.
> 
> fyi, active is always set to true
> 
> I agree the argument to api is poorly labeled. It should be labeled as flip
> or something on those lines?

If it is always true, then it should be dropped instead of renaming it.

> 
> 
> thanks,
> Srini
> > > +			dev_err(component->dev, "Unable to select us/euro mux state\n");
> > > +	}
> > >   	return true;
> > >   }
> > 

-- 
With best wishes
Dmitry