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

On 8/14/26 8:26 PM, Ralph Siemsen wrote:
> Add simple recursion support to the .set_state method. This makes it
> possible to use subgroups in the device tree, which in turn allows
> setting multiple pins with different bias/drive-strength properties.
> 
> Fixes: e4aea57fa773 ("pinctrl: renesas: add R906G032 driver")
> Signed-off-by: Ralph Siemsen <[email protected]>
> ---
> Changes in v2:
> - split out of the series "Renesas RZ/N1 additional drivers"
>    https://lore.kernel.org/u-boot/[email protected]/
> - fix typos in commit message
> - use device_foreach_child() to iterate child nodes
> - move recursion to top of function, ahead of the early return in the
>    case of no direct pinmux entries, instead of removing early return.
> - dev_err() in case of failure during recursion
> ---
>   drivers/pinctrl/renesas/pinctrl-rzn1.c | 13 +++++++++++++
>   1 file changed, 13 insertions(+)
> 
> 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 ?