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

On 8/15/26 3:53 PM, Ralph Siemsen wrote:
> 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.
Let's go with bounded one-level-deep parsing, that's what the bindings 
describe too.