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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Russell King <linux@armlinux.org.uk>,
        Linus Walleij <linus.walleij@linaro.org>,
        Jacek Anaszewski <jacek.anaszewski@gmail.com>,
        Pavel Machek <pavel@ucw.cz>
Subject: [PATCH 5.4 074/104] leds: gpio: Fix uninitialized gpio label for fwnode based probe
Date:   Tue, 28 Jan 2020 15:00:35 +0100
Message-Id: <20200128135827.510578407@linuxfoundation.org>
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From: Jacek Anaszewski <jacek.anaszewski@gmail.com>

commit 90a8e82d3ca8c1f85ac63f4a94c9b034f05af4ee upstream.

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: Russell King <linux@armlinux.org.uk>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
[fixed comment]
Signed-off-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/leds/leds-gpio.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

--- a/drivers/leds/leds-gpio.c
+++ b/drivers/leds/leds-gpio.c
@@ -151,9 +151,14 @@ static struct gpio_leds_priv *gpio_leds_
 		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_
 			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++;
 	}