A recent change added support for looking up an optional mux control
before falling back to gpio control for us-euro plug selection.

The mux framework does however not yet support optional muxes and an
error message is now incorrectly logged on machines like the Lenovo
ThinkPad X13s which do not have one:

    wcd938x_codec audio-codec: /audio-codec: failed to get mux-control (0)

Suppress the bogus error and add the missing mux error handling by
making sure that the 'mux-controls' DT property is present before
looking up the mux control.

Fixes: eec611d26f84 ("ASoC: codecs: wcd938x: add mux control support for hp audio mux")
Link: https://lore.kernel.org/lkml/Z-z_ZAyVBK5ui50k@hovoldconsulting.com/
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
 sound/soc/codecs/wcd938x.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/sound/soc/codecs/wcd938x.c b/sound/soc/codecs/wcd938x.c
index 585a92772c2a..55031c16e4e1 100644
--- a/sound/soc/codecs/wcd938x.c
+++ b/sound/soc/codecs/wcd938x.c
@@ -3271,18 +3271,13 @@ 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_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;
+	if (of_property_present(dev->of_node, "mux-controls")) {
+		wcd938x->us_euro_mux = devm_mux_control_get(dev, NULL);
+		if (IS_ERR(wcd938x->us_euro_mux)) {
+			ret = PTR_ERR(wcd938x->us_euro_mux);
+			return dev_err_probe(dev, ret, "failed to get mux control\n");
+		}
 
-		/* 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);
@@ -3290,6 +3285,11 @@ static int wcd938x_populate_dt_data(struct wcd938x_priv *wcd938x, struct device
 			return ret;
 		}
 		wcd938x->mux_setup_done = true;
+	} else {
+		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");
 	}
 
 	cfg->swap_gnd_mic = wcd938x_swap_gnd_mic;
-- 
2.49.0

…
> +++ b/sound/soc/codecs/wcd938x.c
> @@ -3271,18 +3271,13 @@ 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_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;
> +	if (of_property_present(dev->of_node, "mux-controls")) {
> +		wcd938x->us_euro_mux = devm_mux_control_get(dev, NULL);
> +		if (IS_ERR(wcd938x->us_euro_mux)) {
> +			ret = PTR_ERR(wcd938x->us_euro_mux);
> +			return dev_err_probe(dev, ret, "failed to get mux control\n");
> +		}

May the error code assignment statement be omitted here together with extra curly brackets
(as such a case is demonstrated in a subsequent if branch)?

+			return dev_err_probe(dev, PTR_ERR(wcd938x->us_euro_mux),
+					     "failed to get mux control\n");


Regards,
Markus

On Tue, Apr 15, 2025 at 12:00:33PM +0200, Markus Elfring wrote:
> …
> > +++ b/sound/soc/codecs/wcd938x.c
> > @@ -3271,18 +3271,13 @@ 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_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;
> > +	if (of_property_present(dev->of_node, "mux-controls")) {
> > +		wcd938x->us_euro_mux = devm_mux_control_get(dev, NULL);
> > +		if (IS_ERR(wcd938x->us_euro_mux)) {
> > +			ret = PTR_ERR(wcd938x->us_euro_mux);
> > +			return dev_err_probe(dev, ret, "failed to get mux control\n");
> > +		}
> 
> May the error code assignment statement be omitted here together with extra curly brackets
> (as such a case is demonstrated in a subsequent if branch)?

I considered that, but I prefer using a temporary variable as it is more
readable.

> 
> +			return dev_err_probe(dev, PTR_ERR(wcd938x->us_euro_mux),
> +					     "failed to get mux control\n");

Johan

>> May the error code assignment statement be omitted here together with extra curly brackets
>> (as such a case is demonstrated in a subsequent if branch)?
> 
> I considered that, but I prefer using a temporary variable as it is more readable.
Would your coding style preferences be inconsistent here?

Regards,
Markus