Re: [PATCH v3 5/6] ASoC: codecs: wcd938x: add mux control support for hp audio mux

[Dmitry Baryshkov]

On 24/03/2025 14:04, Srinivas Kandagatla wrote:
> On 24/03/2025 11:20, Dmitry Baryshkov wrote:
> > On 24/03/2025 13:06, srinivas.kandagatla@xxxxxxxxxx wrote:
> > > From: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
> > >
> > > 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@xxxxxxxxxx>
> > > Tested-by: Christopher Obbard <christopher.obbard@xxxxxxxxxx>
> > > ---
> > >   sound/soc/codecs/Kconfig   |  1 +
> > >   sound/soc/codecs/wcd938x.c | 38 ++++++++++++++++++++++++++++++--------
> > >   2 files changed, 31 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/sound/soc/codecs/Kconfig b/sound/soc/codecs/Kconfig
> > > index ee35f3aa5521..a2829d76e108 100644
> > > --- a/sound/soc/codecs/Kconfig
> > > +++ b/sound/soc/codecs/Kconfig
> > > @@ -2226,6 +2226,7 @@ config SND_SOC_WCD938X
> > >       tristate
> > >       depends on SOUNDWIRE || !SOUNDWIRE
> > >       select SND_SOC_WCD_CLASSH
> > > +    select MULTIPLEXER
> > >   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 dfaa3de31164..948b5f6cc45a 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)
> > >       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);
> >
> > Is it possible to use mux_state for both GPIO and MUX paths?
>
> Ideally I would like to do that the way that gpio is done, which is 
> clear reflection of hw state, however mux f/w is lacking such api.

Anyway, both paths should use the same flow.

> > > +    } 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))
> > > +            dev_err(component->dev, "Unable to select us/euro mux 
> > > state\n");
> >
> > This can lead to mux being deselected next time even if the 
> > mux_control_select returned an error. I think mux_control API needs a 
> > way to toggle the state without deselecting it first. Anyway, an error 
> > from mux_control_select() must prevent you from calling 
> > mux_control_deselect() next time.
>
> We can rearrange deselect to be done only on successful select, that 
> should cleanup some of this.

Yes, please.

> --srini
> > > +    }
> > >       return true;
> > >   }


--
With best wishes
Dmitry