Re: [PATCH v4 5/6] ASoC: codecs: wcd938x: add mux control support for hp audio mux

[Srinivas Kandagatla <srinivas.kandagatla@linaro.org>]

On 24/03/2025 13:50, Dmitry Baryshkov wrote:
> On Mon, 24 Mar 2025 at 15:01, <srinivas.kandagatla@linaro.org> wrote:
>>
>> From: Srinivas Kandagatla <srinivas.kandagatla@linaro.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@linaro.org>
>> Tested-by: Christopher Obbard <christopher.obbard@linaro.org>
>> ---
>>   sound/soc/codecs/Kconfig   |  1 +
>>   sound/soc/codecs/wcd938x.c | 50 +++++++++++++++++++++++++++++---------
>>   2 files changed, 40 insertions(+), 11 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..88c758efe40d 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;
>> @@ -3235,17 +3238,31 @@ static void wcd938x_dt_parse_micbias_info(struct device *dev, struct wcd938x_pri
>>                  dev_info(dev, "%s: Micbias4 DT property not found\n", __func__);
>>   }
>>
>> -static bool wcd938x_swap_gnd_mic(struct snd_soc_component *component)
>> +static int wcd938x_select_mux_state(struct device *dev, struct wcd938x_priv *wcd938x, int state)
>>   {
>> -       int value;
>> +       int ret = mux_control_try_select(wcd938x->us_euro_mux, state);
> 
> Hmm. Does this really work? You have selected the mux in probe
> function, now you are trying to select it again. If I'm reading the
> code correctly, you will get -EBUSY here.

On successful selection of mux state, the mux will be kept available 
(mux_control_deselect) for any new callers.

So we will not get EBUSY for the second caller.

--srini
> 
>>
>> -       struct wcd938x_priv *wcd938x;
>> +       if (ret) {
>> +               dev_err(dev, "Error (%d) Unable to select us/euro mux state\n", ret);
>> +               return ret;
>> +       }
>>
>> -       wcd938x = snd_soc_component_get_drvdata(component);
>> +       wcd938x->mux_state = state;
>> +       mux_control_deselect(wcd938x->us_euro_mux);
>> +
>> +       return 0;
>> +}
>>
>> -       value = gpiod_get_value(wcd938x->us_euro_gpio);
>> +static bool wcd938x_swap_gnd_mic(struct snd_soc_component *component)
>> +{
>> +       struct wcd938x_priv *wcd938x = snd_soc_component_get_drvdata(component);
>>
>> -       gpiod_set_value(wcd938x->us_euro_gpio, !value);
>> +       if (wcd938x->us_euro_mux) {
>> +               if (wcd938x_select_mux_state(component->dev, wcd938x, !wcd938x->mux_state))
>> +                       return false;
>> +       } else {
>> +               gpiod_set_value(wcd938x->us_euro_gpio, !wcd938x->mux_state);
>> +       }
>>
>>          return true;
>>   }
>> @@ -3261,11 +3278,22 @@ static int wcd938x_populate_dt_data(struct wcd938x_priv *wcd938x, struct device
>>                  return dev_err_probe(dev, wcd938x->reset_gpio,
>>                                       "Failed to get reset gpio\n");
>>
>> -       wcd938x->us_euro_gpio = devm_gpiod_get_optional(dev, "us-euro",
>> -                                               GPIOD_OUT_LOW);
>> -       if (IS_ERR(wcd938x->us_euro_gpio))
>> -               return dev_err_probe(dev, PTR_ERR(wcd938x->us_euro_gpio),
>> -                                    "us-euro swap Control GPIO not found\n");
>> +       wcd938x->us_euro_mux = devm_mux_control_get(dev, NULL);
>> +       if (IS_ERR(wcd938x->us_euro_mux)) {
>> +               if (PTR_ERR(wcd938x->us_euro_mux) == -EPROBE_DEFER)
>> +                       return -EPROBE_DEFER;
>> +
>> +               /* mux is optional and now fallback to using gpio */
>> +               wcd938x->us_euro_mux = NULL;
>> +               wcd938x->us_euro_gpio = devm_gpiod_get_optional(dev, "us-euro", GPIOD_OUT_LOW);
>> +               if (IS_ERR(wcd938x->us_euro_gpio))
>> +                       return dev_err_probe(dev, PTR_ERR(wcd938x->us_euro_gpio),
>> +                                            "us-euro swap Control GPIO not found\n");
>> +       } else {
>> +               ret = wcd938x_select_mux_state(dev, wcd938x, wcd938x->mux_state);
>> +               if (ret)
>> +                       return ret;
>> +       }
>>
>>          cfg->swap_gnd_mic = wcd938x_swap_gnd_mic;
>>
>> --
>> 2.39.5
>>
> 
>