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

[Srinivas Kandagatla]

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@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>
>
> > @@ -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.

--srini

> > +	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 = mux_control_try_select(wcd938x->us_euro_mux, wcd938x->mux_state);
> > +		if (ret) {
> > +			dev_err(dev, "Error (%d) Unable to select us/euro mux state\n", ret);
> > +			wcd938x->mux_setup_done = false;
> > +			return ret;
> > +		}
> > +		wcd938x->mux_setup_done = true;
> > +	}
>
> Johan