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From: Geert Uytterhoeven <>
To: Linus Walleij <>,
	Bartosz Golaszewski <>
	Geert Uytterhoeven <>
Subject: [PATCH] gpiolib: Document that GPIO line names are not globally unique
Date: Mon, 11 May 2020 12:18:28 +0200	[thread overview]
Message-ID: <> (raw)

gpiochip_set_desc_names() no longer rejects GPIO line name collisions.
Hence GPIO line names are not guaranteed to be globally unique.
In case of multiple GPIO lines with the same name, gpio_name_to_desc()
will return the first match found.

Update the comments for gpio_name_to_desc() and
gpiochip_set_desc_names() to match reality.

Fixes: f881bab038c9667d ("gpio: keep the GPIO line names internal")
Signed-off-by: Geert Uytterhoeven <>
 drivers/gpio/gpiolib.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 99533f4cb5d332a9..98822412f565073a 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -296,6 +296,9 @@ static int gpiodev_add_to_list(struct gpio_device *gdev)
  * Convert a GPIO name to its descriptor
+ * Note that there is no guarantee that GPIO names are globally unique!
+ * Hence this function will return, if it exists, a reference to the first GPIO
+ * line found that matches the given name.
 static struct gpio_desc *gpio_name_to_desc(const char * const name)
@@ -329,10 +332,12 @@ static struct gpio_desc *gpio_name_to_desc(const char * const name)
- * Takes the names from gc->names and checks if they are all unique. If they
- * are, they are assigned to their gpio descriptors.
+ * Take the names from gc->names and assign them to their GPIO descriptors.
+ * Warn if a name is already used for a GPIO line on a different GPIO chip.
- * Warning if one of the names is already used for a different GPIO.
+ * Note that:
+ *   1. Non-unique names are still accepted,
+ *   2. Name collisions within the same GPIO chip are not reported.
 static int gpiochip_set_desc_names(struct gpio_chip *gc)

             reply	other threads:[~2020-05-11 10:18 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-11 10:18 Geert Uytterhoeven [this message]
2020-05-12 10:43 ` Bartosz Golaszewski
2020-05-16  9:41   ` Linus Walleij
2020-05-16  9:37 ` Linus Walleij

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