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

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

[Jacek Anaszewski]

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@linaro.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.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

Re: [PATCH] leds: gpio: Fix uninitialized gpio label for fwnode based probe

[Linus Walleij]

On Thu, Dec 5, 2019 at 10:25 PM Jacek Anaszewski
<jacek.anaszewski@gmail.com> wrote:

> 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@linaro.org>
> Cc: Pavel Machek <pavel@ucw.cz>
> Cc: Russell King <linux@armlinux.org.uk>
> Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij

Re: [PATCH] leds: gpio: Fix uninitialized gpio label for fwnode based probe

[Pavel Machek]

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Hi!

> 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@linaro.org>
> Cc: Pavel Machek <pavel@ucw.cz>
> Cc: Russell King <linux@armlinux.org.uk>
> Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>

Patch looks good, except:

> @@ -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);

This is not linuxdoc, so comment should beging with /* AFAICT.

I'll probably hand-edit the patch.

Best regards,
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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Re: [PATCH] leds: gpio: Fix uninitialized gpio label for fwnode based probe

[Jacek Anaszewski]

On 12/21/19 7:49 PM, Pavel Machek wrote:
> Hi!
> 
>> 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@linaro.org>
>> Cc: Pavel Machek <pavel@ucw.cz>
>> Cc: Russell King <linux@armlinux.org.uk>
>> Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
> 
> Patch looks good, except:
> 
>> @@ -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);
> 
> This is not linuxdoc, so comment should beging with /* AFAICT.

Right.

> I'll probably hand-edit the patch.

Sure, thanks.

-- 
Best regards,
Jacek Anaszewski