linux-kernel - [RFC PATCH v2] gpio: sysfs: make the sysfs export behavior consistent

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Message-ID: <20240930083029.17694-1-brgl@bgdev.pl>
Date: Mon, 30 Sep 2024 10:30:29 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Linus Walleij <linus.walleij@...aro.org>,
	Kent Gibson <warthog618@...il.com>
Cc: linux-gpio@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: [RFC PATCH v2] gpio: sysfs: make the sysfs export behavior consistent

From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

For drivers or board files that set gpio_chip->names, the links to the
GPIO attribute group created on sysfs export will be named after the
line's name set in that array. For lines that are named using device
properties, the names pointer of the gpio_chip struct is never assigned
so they are exported as if they're not named.

The ABI documentation does not mention the former behavior and given
that the majority of modern systems use device-tree, ACPI or other way
of passing GPIO names using device properties - bypassing gc->names -
it's better to make the behavior consistent by always exporting lines as
"gpioXYZ".

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
v1 -> v2:
- remove the no longer needed ioname variable

 drivers/gpio/gpiolib-sysfs.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 17ed229412af..20426d6e04d5 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -573,11 +573,10 @@ static struct class gpio_class = {
  */
 int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 {
-	const char *ioname = NULL;
 	struct gpio_device *gdev;
 	struct gpiod_data *data;
 	struct device *dev;
-	int status, offset;
+	int status;
 
 	/* can't export until sysfs is available ... */
 	if (!class_is_registered(&gpio_class)) {
@@ -626,14 +625,9 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 	else
 		data->direction_can_change = false;
 
-	offset = gpio_chip_hwgpio(desc);
-	if (guard.gc->names && guard.gc->names[offset])
-		ioname = guard.gc->names[offset];
-
 	dev = device_create_with_groups(&gpio_class, &gdev->dev,
 					MKDEV(0, 0), data, gpio_groups,
-					ioname ? ioname : "gpio%u",
-					desc_to_gpio(desc));
+					"gpio%u", desc_to_gpio(desc));
 	if (IS_ERR(dev)) {
 		status = PTR_ERR(dev);
 		goto err_free_data;
-- 
2.43.0