Re: [PATCH v2 2/2] dt-bindings: mfd: twl4030-audio: document preferred name for external mute

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] dt-bindings: mfd: twl4030-audio: legacy ti,hs_extmute_gpio not parsed by gpiolib
--

commit 532ee39ea30fdb221d903a6c57f70fe4aec67890
Author: Dmitry Torokhov <dmitry.torokhov@gmail.com>

dt-bindings: mfd: twl4030-audio: document preferred name for external mute

This commit documents ti,hs_extmute-gpios as the preferred property name for
the external headset mute GPIO in the twl4030-audio binding and marks
ti,hs_extmute_gpio as deprecated.

> diff --git a/Documentation/devicetree/bindings/sound/ti,twl4030-audio.yaml b/Documentation/devicetree/bindings/sound/ti,twl4030-audio.yaml
> index c9c3f7513ad42..399693bed077a 100644
> --- a/Documentation/devicetree/bindings/sound/ti,twl4030-audio.yaml
> +++ b/Documentation/devicetree/bindings/sound/ti,twl4030-audio.yaml
> @@ -39,10 +39,16 @@ properties:
>          description:
>            Enable the use of an external mute for headset pop reduction.
>  
> +      ti,hs_extmute-gpios:
> +        description:
> +          The GPIO specifier for the external mute control.
> +        maxItems: 1
> +
>        ti,hs_extmute_gpio:
>          $ref: /schemas/types.yaml#/definitions/phandle-array
>          description:
> -          The GPIO specifier for the external mute control.
> +          Deprecated legacy name for ti,hs_extmute-gpios.
> +        deprecated: true
>          maxItems: 1

[Severity: Medium]
Does gpiolib actually resolve the deprecated ti,hs_extmute_gpio property
(with an underscore before gpio) when the driver requests con_id
"ti,hs_extmute"?

In sound/soc/codecs/twl4030.c, twl4030_get_board_params() requests the GPIO
via:

	/*
	 * This will attempt to parse "ti,hs_extmute-gpios" or
	 * "ti,hs_extmute_gpio".
	 */
	params->hs_extmute_gpio = devm_fwnode_gpiod_get_optional(dev, codec_node,
								 "ti,hs_extmute",
								 GPIOD_OUT_LOW,
								 "hs_extmute");

However, of_find_gpio() builds property names using
for_each_gpio_property_name() in drivers/gpio/gpiolib.h, which formats
candidates with a hyphen separator over gpio_suffixes[] ("gpios" and "gpio"):

	if (con_id)
		snprintf(propname, sizeof(propname), "%s-%s", con_id, __gs);

For con_id "ti,hs_extmute", gpiolib only checks "ti,hs_extmute-gpios" and
"ti,hs_extmute-gpio", not "ti,hs_extmute_gpio", and of_find_gpio_rename() in
drivers/gpio/gpiolib-of.c has no rename entry for this property.

On device trees using the legacy ti,hs_extmute_gpio property, such as
twl_audio in arch/arm/boot/dts/ti/omap/logicpd-som-lv.dtsi:

	twl_audio: audio {
		compatible = "ti,twl4030-audio";
		codec {
			ti,hs_extmute_gpio = <&gpio2 25 GPIO_ACTIVE_HIGH>;
		};
	};

devm_fwnode_gpiod_get_optional() will return NULL, leaving external headset
mute disabled or configuring the internal TWL4030_PMBR1_REG EXTMUTE mux
instead of driving the external GPIO when ti,hs_extmute is also present.

Should the driver fall back to requesting the legacy property name (or add a
quirk in gpiolib-of.c) so that existing device trees using ti,hs_extmute_gpio
continue to work?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261027-twl4030-extmute-v2-0-c7e0c90509a1@gmail.com?part=2