linux-kernel - Re: [PATCH 1/3] video / backlight: add two APIs for drivers to use

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Date:	Sat, 03 Jan 2015 10:04:40 +0900
From:	Jingoo Han <jg1.han@...sung.com>
To:	'Aaron Lu' <aaron.lu@...el.com>
Cc:	'Lee Jones' <lee.jones@...aro.org>,
	'Zhang Rui' <rui.zhang@...el.com>,
	"'Rafael J. Wysocki'" <rjw@...ysocki.net>,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org, 'Jingoo Han' <jg1.han@...sung.com>
Subject: Re: [PATCH 1/3] video / backlight: add two APIs for drivers to use

On Wednesday, December 31, 2014 12:50 PM, Aaron Lu wrote:
> 
> It is useful to get the backlight device's pointer and use it to set
> backlight in some cases(the following patch will make use of it) so add
> the two APIs and export them.
> 
> Signed-off-by: Aaron Lu <aaron.lu@...el.com>

Acked-by: Jingoo Han <jg1.han@...sung.com>

Best regards,
Jingoo Han

> ---
>  drivers/video/backlight/backlight.c | 44 ++++++++++++++++++++++++-------------
>  include/linux/backlight.h           |  2 ++
>  2 files changed, 31 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
> index bddc8b17a4d8..bea749329236 100644
> --- a/drivers/video/backlight/backlight.c
> +++ b/drivers/video/backlight/backlight.c
> @@ -164,28 +164,19 @@ static ssize_t brightness_show(struct device *dev,
>  	return sprintf(buf, "%d\n", bd->props.brightness);
>  }
> 
> -static ssize_t brightness_store(struct device *dev,
> -		struct device_attribute *attr, const char *buf, size_t count)
> +int backlight_device_set_brightness(struct backlight_device *bd, int brightness)
>  {
> -	int rc;
> -	struct backlight_device *bd = to_backlight_device(dev);
> -	unsigned long brightness;
> -
> -	rc = kstrtoul(buf, 0, &brightness);
> -	if (rc)
> -		return rc;
> -
> -	rc = -ENXIO;
> +	int rc = -ENXIO;
> 
>  	mutex_lock(&bd->ops_lock);
>  	if (bd->ops) {
>  		if (brightness > bd->props.max_brightness)
>  			rc = -EINVAL;
>  		else {
> -			pr_debug("set brightness to %lu\n", brightness);
> +			pr_debug("set brightness to %u\n", brightness);
>  			bd->props.brightness = brightness;
>  			backlight_update_status(bd);
> -			rc = count;
> +			rc = 0;
>  		}
>  	}
>  	mutex_unlock(&bd->ops_lock);
> @@ -194,6 +185,23 @@ static ssize_t brightness_store(struct device *dev,
> 
>  	return rc;
>  }
> +EXPORT_SYMBOL(backlight_device_set_brightness);
> +
> +static ssize_t brightness_store(struct device *dev,
> +		struct device_attribute *attr, const char *buf, size_t count)
> +{
> +	int rc;
> +	struct backlight_device *bd = to_backlight_device(dev);
> +	unsigned long brightness;
> +
> +	rc = kstrtoul(buf, 0, &brightness);
> +	if (rc)
> +		return rc;
> +
> +	rc = backlight_device_set_brightness(bd, brightness);
> +
> +	return rc ? rc : count;
> +}
>  static DEVICE_ATTR_RW(brightness);
> 
>  static ssize_t type_show(struct device *dev, struct device_attribute *attr,
> @@ -380,7 +388,7 @@ struct backlight_device *backlight_device_register(const char *name,
>  }
>  EXPORT_SYMBOL(backlight_device_register);
> 
> -bool backlight_device_registered(enum backlight_type type)
> +struct backlight_device *backlight_device_get_by_type(enum backlight_type type)
>  {
>  	bool found = false;
>  	struct backlight_device *bd;
> @@ -394,7 +402,13 @@ bool backlight_device_registered(enum backlight_type type)
>  	}
>  	mutex_unlock(&backlight_dev_list_mutex);
> 
> -	return found;
> +	return found ? bd : NULL;
> +}
> +EXPORT_SYMBOL(backlight_device_get_by_type);
> +
> +bool backlight_device_registered(enum backlight_type type)
> +{
> +	return backlight_device_get_by_type(type) ? true : false;
>  }
>  EXPORT_SYMBOL(backlight_device_registered);
> 
> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
> index adb14a8616df..c59a020df3f8 100644
> --- a/include/linux/backlight.h
> +++ b/include/linux/backlight.h
> @@ -140,6 +140,8 @@ extern void backlight_force_update(struct backlight_device *bd,
>  extern bool backlight_device_registered(enum backlight_type type);
>  extern int backlight_register_notifier(struct notifier_block *nb);
>  extern int backlight_unregister_notifier(struct notifier_block *nb);
> +extern struct backlight_device *backlight_device_get_by_type(enum backlight_type type);
> +extern int backlight_device_set_brightness(struct backlight_device *bd, int brightness);
> 
>  #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
> 
> --
> 2.1.0

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