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

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Message-ID: <cxnmq66gww5mopwwbnw34gx4ynoocf63c76lwwn6h7eklzxhap@whjsxav7nggf>
Date: Fri, 21 Mar 2025 18:34:35 +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 01:26:44PM +0000, Srinivas Kandagatla wrote:
> 
> 
> On 21/03/2025 13:16, Dmitry Baryshkov wrote:
> > On Fri, 21 Mar 2025 at 14:35, Srinivas Kandagatla
> > <srinivas.kandagatla@...aro.org> 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?
> > > 
> > > We want to move the codec to use gpio mux instead of using gpios directly
> > > 
> > > So this become codec specific, rather than platform.
> > 
> > Not quite. "select MULTIPLEXER" is correct and is not questionable.
> > I'm asking about the MUX_GPIO. The codec itself has nothing to do with
> > the board using _GPIO_ to switch 4-pin modes. It is a board-level
> > decision. A board can use an I2C-controlled MUX instead. I'd say, that
> > at least you should describe rationale for this `imply` clause in the
> > commit message.
> 
> I agree to you point, but historically in this case us/euro selection is
> only driven by gpio. But I see no harm in moving the MUX_GPIO dependency to
> machine driver KConfigs.

Machine driver also doesn't depend on it. MUX_GPIO is selectedable item,
so please handle it via the usual way - defconfig.

-- 
With best wishes
Dmitry