linux-kernel - [PATCH] leds: gpio: Fix uninitialized gpio label for fwnode based probe

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Date:   Thu,  5 Dec 2019 22:25:01 +0100
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     linux-leds@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, jacek.anaszewski@...il.com,
        Linus Walleij <linus.walleij@...aro.org>,
        Pavel Machek <pavel@....cz>,
        Russell King <linux@...linux.org.uk>
Subject: [PATCH] leds: gpio: Fix uninitialized gpio label for fwnode based probe

When switching to using generic LED name composition mechanism via
devm_led_classdev_register_ext() API the part of code initializing
struct gpio_led's template name property was removed alongside.
It was however overlooked that the property was also passed to
devm_fwnode_get_gpiod_from_child() in place of "label" parameter,
which when set to NULL, results in gpio label being initialized to '?'.

It could be observed in debugfs and failed to properly identify
gpio association with LED consumer.

Fix this shortcoming by updating the GPIO label after the LED is
registered and its final name is known.

Fixes: d7235f5feaa0 ("leds: gpio: Use generic support for composing LED names")
Cc: Linus Walleij <linus.walleij@...aro.org>
Cc: Pavel Machek <pavel@....cz>
Cc: Russell King <linux@...linux.org.uk>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@...il.com>
---
 drivers/leds/leds-gpio.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/leds/leds-gpio.c b/drivers/leds/leds-gpio.c
index a5c73f3d5f79..43eeed096d0d 100644
--- a/drivers/leds/leds-gpio.c
+++ b/drivers/leds/leds-gpio.c
@@ -151,9 +151,14 @@ static struct gpio_leds_priv *gpio_leds_create(struct platform_device *pdev)
 		struct gpio_led led = {};
 		const char *state = NULL;
 
+		/**
+		 * Acquire gpiod from DT with uninitialized label, which
+		 * will be updated after LED class device is registered,
+		 * Only then the final LED name is known.
+		 */
 		led.gpiod = devm_fwnode_get_gpiod_from_child(dev, NULL, child,
 							     GPIOD_ASIS,
-							     led.name);
+							     NULL);
 		if (IS_ERR(led.gpiod)) {
 			fwnode_handle_put(child);
 			return ERR_CAST(led.gpiod);
@@ -186,6 +191,9 @@ static struct gpio_leds_priv *gpio_leds_create(struct platform_device *pdev)
 			fwnode_handle_put(child);
 			return ERR_PTR(ret);
 		}
+		/* Set gpiod label to match the corresponding LED name. */
+		gpiod_set_consumer_name(led_dat->gpiod,
+					led_dat->cdev.dev->kobj.name);
 		priv->num_leds++;
 	}
 
-- 
2.11.0