Re: [PATCH] gpiolib: use of_node_name if line-name is missing

["Frank Wunderlich (linux)" <linux@fw-web.de>]

Am 2026-09-17 15:00, schrieb Andy Shevchenko:
> On Thu, Sep 17, 2026 at 02:28:13PM +0200, Frank Wunderlich wrote:
> 
>> Until v7.0, GPIO hogs inherited the DT node name when no line-name
>> property was specified. This was implemented as a fallback in
>> of_parse_own_gpio().
>> 
>> Commit d1d564ec4992 ("gpio: move hogs into GPIO core") moved hog 
>> parsing
>> into the GPIO core and removed this fallback.
>> 
>> Consequently, GPIO hogs without a line-name property are now displayed
>> with a ? in /sys/kernel/debug/gpio. Restore the old fallback.
> 
> ...
> 
>> int gpiochip_add_hog(struct gpio_chip *gc, struct fwnode_handle 
>> *fwnode)
> 
>>  	fwnode_property_read_string(fwnode, "line-name", &name);
>> 
>> +	if (!name && is_of_node(fwnode))
>> +		name = to_of_node(fwnode)->name;
> 
> Can we move it inside the loop? Yes, I understand that it will be 
> unnecessarily
> called more times than required, but gpiod_hog() is called anyway in 
> the loop,
> so I don't think it will be a big deal. With that it will allow to 
> group
> OF-specific code in one location.
> 
>>  	for (unsigned int i = 0; i < num_hogs; i++) {
>>  		if (is_of_node(fwnode)) {
> 
> 		...somewhere inside this conditional...
> 
>>  			/*

I'm not sure what you want to achieve here (maybe only to have the 
is_of_node-condition once?, as the loop imho is only for enumerating 
multiple gpio (like "gpios = <3 0>, <4 0>;") inside one hog of_node. 
Here the node-name will never change (like the line-name above) and 
read-once is correct.
But while looking at the code i also thought about these multi-gpio-hogs 
(label and output-X). Imho here something like the gpio-controllers 
"line-names" would make sense as well as something similar for the 
output (or just handling this with the GPIO_ACTIVE_HIGH/LOW param).

But if you think the part should be moved into the loop, that's no big 
deal.

regards Frank