linux-kernel - Re: [PATCH v6 5/6] ASoC: codecs: wcd938x: add mux control support for hp audio mux

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Message-ID: <6e135e55-b5e4-4ead-85ba-29c2cd6aa7a2@oss.qualcomm.com>
Date: Sat, 5 Apr 2025 20:27:47 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Johan Hovold <johan@...nel.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,
        Christopher Obbard <christopher.obbard@...aro.org>
Subject: Re: [PATCH v6 5/6] ASoC: codecs: wcd938x: add mux control support for
 hp audio mux

On 03/04/2025 15:19, Srinivas Kandagatla wrote:
> 
> 
> On 02/04/2025 10:12, Johan Hovold wrote:
>> On Thu, Mar 27, 2025 at 10:06:32AM +0000, Srinivas Kandagatla 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>
>>
>>> @@ -3261,11 +3276,26 @@ 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);
>>
> Thanks Johan,
>> Running with this patch on the CRD I noticed that this now prints an
>> error as there is no optional mux (or gpio) defined:
>>
>>     wcd938x_codec audio-codec: /audio-codec: failed to get mux-control 
>> (0)
> 
> This is not from codec driver, mux control is throwing up this.
> 
>>
>> You need to suppress that error in mux_get() to allow for optional muxes
>> to be looked up like this.
> I have a plan for this,
> 
> I proposed some changes to mux api for exclusive apis at https:// 
> lkml.org/lkml/2025/3/26/955
> 
> This should also allow us to easily add an optional api, which I plan to 
> do once i get some feedback on this patch.

I'd rather suggest an API to switch the state without deselecting the 
the mux.

> 
> --srini
> 
>>

-- 
With best wishes
Dmitry