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: <aPkmDWJEKrjlMPnD@smile.fi.intel.com>
Date: Wed, 22 Oct 2025 21:44:29 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Bartosz Golaszewski <brgl@...ev.pl>
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 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)

> +	return no_free_ptr(gdev);
>  }

-- 
With Best Regards,
Andy Shevchenko