linux-kernel - Re: [PATCH v2 4/9] gpio: swnode: don't use the swnode's name as the key for GPIO lookup

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Message-ID: <CAMRc=MeNNGXy6aAanLnbWFYJiK65dvm_HyjCDS1=LZ4RiA4GAA@mail.gmail.com>
Date: Fri, 24 Oct 2025 09:17:25 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Linus Walleij <linus.walleij@...aro.org>, Daniel Scally <djrscally@...il.com>, 
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>, 
	Sakari Ailus <sakari.ailus@...ux.intel.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, "Rafael J. Wysocki" <rafael@...nel.org>, 
	Danilo Krummrich <dakr@...nel.org>, Philipp Zabel <p.zabel@...gutronix.de>, 
	Krzysztof Kozlowski <krzk@...nel.org>, linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-acpi@...r.kernel.org, 
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v2 4/9] gpio: swnode: don't use the swnode's name as the
 key for GPIO lookup

On Wed, Oct 22, 2025 at 8:44 PM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
>
> On Wed, Oct 22, 2025 at 03:41:03PM +0200, Bartosz Golaszewski wrote:
> >
> > Looking up a GPIO controller by label that is the name of the software
> > node is wonky at best - the GPIO controller driver is free to set
> > a different label than the name of its firmware node. We're already being
> > passed a firmware node handle attached to the GPIO device to
> > swnode_get_gpio_device() so use it instead for a more precise lookup.
>
> ...
>
> >  static struct gpio_device *swnode_get_gpio_device(struct fwnode_handle *fwnode)
> >  {
> > +     struct gpio_device *gdev __free(gpio_device_put) =
> > +                                     gpio_device_find_by_fwnode(fwnode);
> > +     if (!gdev)
> > +             return ERR_PTR(-EPROBE_DEFER);
> >
> >       /*
> >        * Check for a special node that identifies undefined GPIOs, this is
> >        * primarily used as a key for internal chip selects in SPI bindings.
> >        */
> >       if (IS_ENABLED(CONFIG_GPIO_SWNODE_UNDEFINED) &&
> > +         !strcmp(fwnode_get_name(fwnode), GPIOLIB_SWNODE_UNDEFINED_NAME))
> >               return ERR_PTR(-ENOENT);
>
> Now we might get EPROBE_DEREF for the cases when previously it was ENOENT.
> Why is this not a problem? (I haven't found the answer neither in the comment
> above, nor in the commit message)
>

Yeah, maybe it should only change the last part from looking up by
label to looking up by fwnode and leave the previous checks in place.

Bart