linux-kernel - Re: [PATCH 19/21] gpio: swnode: replace gpiochip_find() with gpio_device_find_by

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Date: Wed, 24 Jan 2024 15:59:22 +0100
From: Paul Cercueil <paul@...pouillou.net>
To: Bartosz Golaszewski <brgl@...ev.pl>, Aaro Koskinen
 <aaro.koskinen@....fi>,  Janusz Krzysztofik <jmkrzyszt@...il.com>, Tony
 Lindgren <tony@...mide.com>, Russell King <linux@...linux.org.uk>, Mika
 Westerberg <mika.westerberg@...ux.intel.com>,  Andy Shevchenko
 <andriy.shevchenko@...ux.intel.com>, Linus Walleij
 <linus.walleij@...aro.org>, Dipen Patel <dipenp@...dia.com>, Thierry Reding
 <thierry.reding@...il.com>, Jonathan Hunter <jonathanh@...dia.com>, Hans de
 Goede <hdegoede@...hat.com>, Mark Gross <markgross@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org, 
	linux-acpi@...r.kernel.org, timestamp@...ts.linux.dev, 
	linux-tegra@...r.kernel.org, platform-driver-x86@...r.kernel.org, Bartosz
	Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH 19/21] gpio: swnode: replace gpiochip_find() with
 gpio_device_find_by_label()

Hi Bartosz,

Le mardi 05 septembre 2023 à 20:53 +0200, Bartosz Golaszewski a écrit :
> From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> 
> We're porting all users of gpiochip_find() to using
> gpio_device_find().
> Update the swnode GPIO code.
> 
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> ---
>  drivers/gpio/gpiolib-swnode.c | 29 ++++++++++++-----------------
>  1 file changed, 12 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/gpio/gpiolib-swnode.c b/drivers/gpio/gpiolib-
> swnode.c
> index b5a6eaf3729b..56c8519be538 100644
> --- a/drivers/gpio/gpiolib-swnode.c
> +++ b/drivers/gpio/gpiolib-swnode.c
> @@ -31,31 +31,26 @@ static void swnode_format_propname(const char
> *con_id, char *propname,
>  		strscpy(propname, "gpios", max_size);
>  }
>  
> -static int swnode_gpiochip_match_name(struct gpio_chip *chip, void
> *data)
> +static struct gpio_device *swnode_get_gpio_device(struct
> fwnode_handle *fwnode)
>  {
> -	return !strcmp(chip->label, data);
> -}
> +	const struct software_node *gdev_node;
> +	struct gpio_device *gdev;
>  
> -static struct gpio_chip *swnode_get_chip(struct fwnode_handle
> *fwnode)
> -{
> -	const struct software_node *chip_node;
> -	struct gpio_chip *chip;
> -
> -	chip_node = to_software_node(fwnode);
> -	if (!chip_node || !chip_node->name)
> +	gdev_node = to_software_node(fwnode);
> +	if (!gdev_node || !gdev_node->name)
>  		return ERR_PTR(-EINVAL);
>  
> -	chip = gpiochip_find((void *)chip_node->name,
> swnode_gpiochip_match_name);
> -	return chip ?: ERR_PTR(-EPROBE_DEFER);
> +	gdev = gpio_device_find_by_label((void *)gdev_node->name);
> +	return gdev ?: ERR_PTR(-EPROBE_DEFER);
>  }
>  
>  struct gpio_desc *swnode_find_gpio(struct fwnode_handle *fwnode,
>  				   const char *con_id, unsigned int
> idx,
>  				   unsigned long *flags)
>  {
> +	struct gpio_device *gdev __free(gpio_device_put) = NULL;
>  	const struct software_node *swnode;
>  	struct fwnode_reference_args args;
> -	struct gpio_chip *chip;
>  	struct gpio_desc *desc;
>  	char propname[32]; /* 32 is max size of property name */
>  	int error;
> @@ -77,12 +72,12 @@ struct gpio_desc *swnode_find_gpio(struct
> fwnode_handle *fwnode,
>  		return ERR_PTR(error);
>  	}
>  
> -	chip = swnode_get_chip(args.fwnode);
> +	gdev = swnode_get_gpio_device(args.fwnode);
>  	fwnode_handle_put(args.fwnode);
> -	if (IS_ERR(chip))
> -		return ERR_CAST(chip);
> +	if (IS_ERR(gdev))
> +		return ERR_CAST(gdev);

I'm a bit late to the party, sorry.

I'm looking at how __free() should be used to use it in my own
patchset, and I was wondering if this code actually works.

What happens if swnode_get_gpio_device() returns an error pointer?
Won't that cause a call to gpio_device_put() with the invalid pointer?

Cheers,
-Paul

>  
> -	desc = gpiochip_get_desc(chip, args.args[0]);
> +	desc = gpiochip_get_desc(gdev->chip, args.args[0]);
>  	*flags = args.args[1]; /* We expect native GPIO flags */
>  
>  	pr_debug("%s: parsed '%s' property of node '%pfwP[%d]' -
> status (%d)\n",