Re: [PATCH v2] pinctrl: renesas: r906g032: handle pin subgroups

[Ralph Siemsen <ralph.siemsen@linaro.org>]

On Sat, Aug 15, 2026 at 12:00:23AM +0200, Marek Vasut wrote:
>>diff --git a/drivers/pinctrl/renesas/pinctrl-rzn1.c 
>>b/drivers/pinctrl/renesas/pinctrl-rzn1.c
>>index fdc43c8e714..6c8d40e9639 100644
>>--- a/drivers/pinctrl/renesas/pinctrl-rzn1.c
>>+++ b/drivers/pinctrl/renesas/pinctrl-rzn1.c
>>@@ -298,11 +298,24 @@ static int rzn1_pinconf_set(struct rzn1_pinctrl_priv *priv, unsigned int pin,
>>  static int rzn1_pinctrl_set_state(struct udevice *dev, struct udevice *config)
>>  {
>>  	struct rzn1_pinctrl_priv *priv = dev_get_priv(dev);
>>+	struct udevice *child;
>>  	int size;
>>  	int ret;
>>  	u32 val;
>>  	u32 bias;
>>+	/*
>>+	 * Handle subnodes recursively, so that pin groups work.
>>+	 * Note that properties are *NOT* inherited from parent.
>>+	 */
>>+	device_foreach_child(child, config) {
>>+		ret = rzn1_pinctrl_set_state(dev, child);

>Can there really be infinite nested subgroups , or are there always 
>only groups with subgroups and that is where it ends ? Linux 
>Documentation/devicetree/bindings/pinctrl/renesas,rzn1-pinctrl.yaml 
>makes it look like the later, so maybe the recursion is not necessary 
>here, instead call device_foreach_child() { device_foreach_child() { .. 
>} } to prevent the possibility of infinite recursion ?

Realistically there will only be groups with one level of subgroups.
Perhaps if there was a phandle it could go a few levels deeper.

Unbounded recursion is not really possible here unless:
- the device tree is infinitely deep, or
- there is a very serious bug in device_foreach_child()

As these both seem unlikely, I opted for the simple recursive call, but 
I am happy to change it if you feel it is better.

Ralph