linux-kernel - Re: [PATCH v8 3/5] leds: Add managed API to get a LED from a device driver

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Date:   Thu, 3 Oct 2019 12:47:11 +0200
From:   Sebastian Reichel <sre@...nel.org>
To:     Jean-Jacques Hiblot <jjhiblot@...com>
Cc:     jacek.anaszewski@...il.com, pavel@....cz, robh+dt@...nel.org,
        mark.rutland@....com, lee.jones@...aro.org,
        daniel.thompson@...aro.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, tomi.valkeinen@...com,
        dmurphy@...com, linux-leds@...r.kernel.org
Subject: Re: [PATCH v8 3/5] leds: Add managed API to get a LED from a device
 driver

Hi,

On Thu, Oct 03, 2019 at 10:28:10AM +0200, Jean-Jacques Hiblot wrote:
> If the LED is acquired by a consumer device with devm_led_get(), it is
> automatically released when the device is detached.
> 
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@...com>
> Acked-by: Pavel Machek <pavel@....cz>
> ---
>  drivers/leds/led-class.c | 49 ++++++++++++++++++++++++++++++++++++++++
>  include/linux/leds.h     |  2 ++
>  2 files changed, 51 insertions(+)
> 
> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
> index 455545f5d663..80c96dd96afc 100644
> --- a/drivers/leds/led-class.c
> +++ b/drivers/leds/led-class.c
> @@ -258,6 +258,55 @@ void led_put(struct led_classdev *led_cdev)
>  }
>  EXPORT_SYMBOL_GPL(led_put);
>  
> +static void devm_led_release(struct device *dev, void *res)
> +{
> +	struct led_classdev **p = res;
> +
> +	led_put(*p);
> +}
> +
> +/**
> + * devm_of_led_get - Resource-managed request of a LED device
> + * @dev:	LED consumer
> + * @index:	index of the LED to obtain in the consumer
> + *
> + * The device node of the device is parse to find the request LED device.
> + * The LED device returned from this function is automatically released
> + * on driver detach.
> + *
> + * @return a pointer to a LED device or ERR_PTR(errno) on failure.
> + */
> +struct led_classdev *__must_check devm_of_led_get(struct device *dev,
> +						  int index)
> +{
> +	struct led_classdev *led;
> +	struct led_classdev **dr;
> +
> +	if (!dev)
> +		return ERR_PTR(-EINVAL);
> +
> +	/* Not using device tree? */
> +	if (!IS_ENABLED(CONFIG_OF) || !dev->of_node)
> +		return ERR_PTR(-ENOTSUPP);

I suggested to move the CONFIG_OF check and the NULL check for
of_node into of_led_get(). Otherwise

Reviewed-by: Sebastian Reichel <sebastian.reichel@...labora.com>

-- Sebastian

> +
> +	led = of_led_get(dev->of_node, index);
> +	if (IS_ERR(led))
> +		return led;
> +
> +	dr = devres_alloc(devm_led_release, sizeof(struct led_classdev *),
> +			  GFP_KERNEL);
> +	if (!dr) {
> +		led_put(led);
> +		return ERR_PTR(-ENOMEM);
> +	}
> +
> +	*dr = led;
> +	devres_add(dev, dr);
> +
> +	return led;
> +}
> +EXPORT_SYMBOL_GPL(devm_of_led_get);
> +
>  static int led_classdev_next_name(const char *init_name, char *name,
>  				  size_t len)
>  {
> diff --git a/include/linux/leds.h b/include/linux/leds.h
> index 6f7371bc7757..9b94cf752012 100644
> --- a/include/linux/leds.h
> +++ b/include/linux/leds.h
> @@ -199,6 +199,8 @@ extern void led_classdev_resume(struct led_classdev *led_cdev);
>  
>  extern struct led_classdev *of_led_get(struct device_node *np, int index);
>  extern void led_put(struct led_classdev *led_cdev);
> +struct led_classdev *__must_check devm_of_led_get(struct device *dev,
> +						  int index);
>  
>  /**
>   * led_blink_set - set blinking with software fallback
> -- 
> 2.17.1
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

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