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

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Message-ID: <ac58b70a-b53a-4c91-8483-1b870623d5e9@linaro.org>
Date: Mon, 24 Mar 2025 12:04:53 +0000
From: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>, peda@...ntia.se,
 broonie@...nel.org, andersson@...nel.org, krzk+dt@...nel.org
Cc: 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,
 Christopher Obbard <christopher.obbard@...aro.org>
Subject: Re: [PATCH v3 5/6] ASoC: codecs: wcd938x: add mux control support for
 hp audio mux



On 24/03/2025 11:20, Dmitry Baryshkov wrote:
> On 24/03/2025 13:06, 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>
>> Tested-by: Christopher Obbard <christopher.obbard@...aro.org>
>> ---
>>   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.


> 
>> +    } 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.

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