diff mbox

[PATCH/RFC,v7,1/3] leds: Add support for setting brightness in a synchronous way

Message ID 1415808557-29557-2-git-send-email-j.anaszewski@samsung.com (mailing list archive)
State New, archived
Headers show

Commit Message

Jacek Anaszewski Nov. 12, 2014, 4:09 p.m. UTC
There are use cases when setting a LED brightness has to
have immediate effect (e.g. setting a torch LED brightness).
This patch extends LED subsystem to support such operations.
The LED subsystem internal API __led_set_brightness is changed
to led_set_brightness_async and new led_set_brightness_sync API
is added.

Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Bryan Wu <cooloney@gmail.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
---
 drivers/leds/led-class.c                  |   10 ++++++----
 drivers/leds/led-core.c                   |   19 ++++++++++++++++---
 drivers/leds/leds.h                       |   20 ++++++++++++++++----
 drivers/leds/trigger/ledtrig-backlight.c  |    8 ++++----
 drivers/leds/trigger/ledtrig-default-on.c |    2 +-
 drivers/leds/trigger/ledtrig-gpio.c       |    6 +++---
 drivers/leds/trigger/ledtrig-heartbeat.c  |    2 +-
 drivers/leds/trigger/ledtrig-oneshot.c    |    4 ++--
 drivers/leds/trigger/ledtrig-transient.c  |   10 ++++++----
 include/linux/leds.h                      |    8 ++++++++
 10 files changed, 63 insertions(+), 26 deletions(-)

Comments

Bryan Wu Nov. 13, 2014, 6:43 p.m. UTC | #1
On Wed, Nov 12, 2014 at 8:09 AM, Jacek Anaszewski
<j.anaszewski@samsung.com> wrote:
> There are use cases when setting a LED brightness has to
> have immediate effect (e.g. setting a torch LED brightness).
> This patch extends LED subsystem to support such operations.
> The LED subsystem internal API __led_set_brightness is changed
> to led_set_brightness_async and new led_set_brightness_sync API
> is added.
>

Great, I do like this patch and just one pick coding style as below.

Thanks,
-Bryan

> Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
> Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
> Cc: Bryan Wu <cooloney@gmail.com>
> Cc: Richard Purdie <rpurdie@rpsys.net>
> ---
>  drivers/leds/led-class.c                  |   10 ++++++----
>  drivers/leds/led-core.c                   |   19 ++++++++++++++++---
>  drivers/leds/leds.h                       |   20 ++++++++++++++++----
>  drivers/leds/trigger/ledtrig-backlight.c  |    8 ++++----
>  drivers/leds/trigger/ledtrig-default-on.c |    2 +-
>  drivers/leds/trigger/ledtrig-gpio.c       |    6 +++---
>  drivers/leds/trigger/ledtrig-heartbeat.c  |    2 +-
>  drivers/leds/trigger/ledtrig-oneshot.c    |    4 ++--
>  drivers/leds/trigger/ledtrig-transient.c  |   10 ++++++----
>  include/linux/leds.h                      |    8 ++++++++
>  10 files changed, 63 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
> index 65722de..dbeebac 100644
> --- a/drivers/leds/led-class.c
> +++ b/drivers/leds/led-class.c
> @@ -55,7 +55,7 @@ static ssize_t brightness_store(struct device *dev,
>
>         if (state == LED_OFF)
>                 led_trigger_remove(led_cdev);
> -       __led_set_brightness(led_cdev, state);
> +       led_set_brightness(led_cdev, state);
>
>         ret = size;
>  unlock:
> @@ -109,7 +109,7 @@ static void led_timer_function(unsigned long data)
>         unsigned long delay;
>
>         if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
> -               __led_set_brightness(led_cdev, LED_OFF);
> +               led_set_brightness_async(led_cdev, LED_OFF);
>                 return;
>         }
>
> @@ -132,7 +132,7 @@ static void led_timer_function(unsigned long data)
>                 delay = led_cdev->blink_delay_off;
>         }
>
> -       __led_set_brightness(led_cdev, brightness);
> +       led_set_brightness_async(led_cdev, brightness);
>
>         /* Return in next iteration if led is in one-shot mode and we are in
>          * the final blink state so that the led is toggled each delay_on +
> @@ -158,7 +158,7 @@ static void set_brightness_delayed(struct work_struct *ws)
>
>         led_stop_software_blink(led_cdev);
>
> -       __led_set_brightness(led_cdev, led_cdev->delayed_set_value);
> +       led_set_brightness_async(led_cdev, led_cdev->delayed_set_value);
>  }
>
>  /**
> @@ -233,6 +233,8 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
>         if (!led_cdev->max_brightness)
>                 led_cdev->max_brightness = LED_FULL;
>
> +       led_cdev->flags |= SET_BRIGHTNESS_ASYNC;
> +
>         led_update_brightness(led_cdev);
>
>         INIT_WORK(&led_cdev->set_brightness_work, set_brightness_delayed);
> diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
> index be6d9fa..a745e32 100644
> --- a/drivers/leds/led-core.c
> +++ b/drivers/leds/led-core.c
> @@ -42,13 +42,13 @@ static void led_set_software_blink(struct led_classdev *led_cdev,
>
>         /* never on - just set to off */
>         if (!delay_on) {
> -               __led_set_brightness(led_cdev, LED_OFF);
> +               led_set_brightness_async(led_cdev, LED_OFF);
>                 return;
>         }
>
>         /* never off - just set to brightness */
>         if (!delay_off) {
> -               __led_set_brightness(led_cdev, led_cdev->blink_brightness);
> +               led_set_brightness_async(led_cdev, led_cdev->blink_brightness);
>                 return;
>         }
>
> @@ -117,6 +117,8 @@ EXPORT_SYMBOL_GPL(led_stop_software_blink);
>  void led_set_brightness(struct led_classdev *led_cdev,
>                         enum led_brightness brightness)
>  {
> +       int ret = 0;
> +
>         /* delay brightness setting if need to stop soft-blink timer */
>         if (led_cdev->blink_delay_on || led_cdev->blink_delay_off) {
>                 led_cdev->delayed_set_value = brightness;
> @@ -124,7 +126,18 @@ void led_set_brightness(struct led_classdev *led_cdev,
>                 return;
>         }
>
> -       __led_set_brightness(led_cdev, brightness);
> +       if (led_cdev->flags & SET_BRIGHTNESS_ASYNC) {
> +               led_set_brightness_async(led_cdev, brightness);
> +               return;
> +       } else if (led_cdev->flags & SET_BRIGHTNESS_SYNC) {
> +               ret = led_set_brightness_sync(led_cdev, brightness);
> +       } else {
> +               ret = -EINVAL;
> +       }
> +

Since there is only one line in the {}, we don't need {} here:

+       if (led_cdev->flags & SET_BRIGHTNESS_ASYNC) {
+               led_set_brightness_async(led_cdev, brightness);
+               return;
+       } else if (led_cdev->flags & SET_BRIGHTNESS_SYNC)
+               ret = led_set_brightness_sync(led_cdev, brightness);
+       else
+               ret = -EINVAL;
+



> +       if (ret < 0)
> +               dev_dbg(led_cdev->dev, "Setting LED brightness failed (%d)\n",
> +                       ret);
>  }
>  EXPORT_SYMBOL(led_set_brightness);
>
> diff --git a/drivers/leds/leds.h b/drivers/leds/leds.h
> index 4c50365..2348dbd 100644
> --- a/drivers/leds/leds.h
> +++ b/drivers/leds/leds.h
> @@ -17,16 +17,28 @@
>  #include <linux/rwsem.h>
>  #include <linux/leds.h>
>
> -static inline void __led_set_brightness(struct led_classdev *led_cdev,
> +static inline void led_set_brightness_async(struct led_classdev *led_cdev,
>                                         enum led_brightness value)
>  {
> -       if (value > led_cdev->max_brightness)
> -               value = led_cdev->max_brightness;
> -       led_cdev->brightness = value;
> +       led_cdev->brightness = min(value, led_cdev->max_brightness);
> +
>         if (!(led_cdev->flags & LED_SUSPENDED))
>                 led_cdev->brightness_set(led_cdev, value);
>  }
>
> +static inline int led_set_brightness_sync(struct led_classdev *led_cdev,
> +                                       enum led_brightness value)
> +{
> +       int ret = 0;
> +
> +       led_cdev->brightness = min(value, led_cdev->max_brightness);
> +
> +       if (!(led_cdev->flags & LED_SUSPENDED))
> +               ret = led_cdev->brightness_set_sync(led_cdev,
> +                                               led_cdev->brightness);
> +       return ret;
> +}
> +
>  static inline int led_get_brightness(struct led_classdev *led_cdev)
>  {
>         return led_cdev->brightness;
> diff --git a/drivers/leds/trigger/ledtrig-backlight.c b/drivers/leds/trigger/ledtrig-backlight.c
> index 47e55aa..59eca17 100644
> --- a/drivers/leds/trigger/ledtrig-backlight.c
> +++ b/drivers/leds/trigger/ledtrig-backlight.c
> @@ -51,9 +51,9 @@ static int fb_notifier_callback(struct notifier_block *p,
>
>         if ((n->old_status == UNBLANK) ^ n->invert) {
>                 n->brightness = led->brightness;
> -               __led_set_brightness(led, LED_OFF);
> +               led_set_brightness_async(led, LED_OFF);
>         } else {
> -               __led_set_brightness(led, n->brightness);
> +               led_set_brightness_async(led, n->brightness);
>         }
>
>         n->old_status = new_status;
> @@ -89,9 +89,9 @@ static ssize_t bl_trig_invert_store(struct device *dev,
>
>         /* After inverting, we need to update the LED. */
>         if ((n->old_status == BLANK) ^ n->invert)
> -               __led_set_brightness(led, LED_OFF);
> +               led_set_brightness_async(led, LED_OFF);
>         else
> -               __led_set_brightness(led, n->brightness);
> +               led_set_brightness_async(led, n->brightness);
>
>         return num;
>  }
> diff --git a/drivers/leds/trigger/ledtrig-default-on.c b/drivers/leds/trigger/ledtrig-default-on.c
> index 81a91be..6f38f88 100644
> --- a/drivers/leds/trigger/ledtrig-default-on.c
> +++ b/drivers/leds/trigger/ledtrig-default-on.c
> @@ -19,7 +19,7 @@
>
>  static void defon_trig_activate(struct led_classdev *led_cdev)
>  {
> -       __led_set_brightness(led_cdev, led_cdev->max_brightness);
> +       led_set_brightness_async(led_cdev, led_cdev->max_brightness);
>  }
>
>  static struct led_trigger defon_led_trigger = {
> diff --git a/drivers/leds/trigger/ledtrig-gpio.c b/drivers/leds/trigger/ledtrig-gpio.c
> index c86c418..4cc7040 100644
> --- a/drivers/leds/trigger/ledtrig-gpio.c
> +++ b/drivers/leds/trigger/ledtrig-gpio.c
> @@ -54,12 +54,12 @@ static void gpio_trig_work(struct work_struct *work)
>
>         if (tmp) {
>                 if (gpio_data->desired_brightness)
> -                       __led_set_brightness(gpio_data->led,
> +                       led_set_brightness_async(gpio_data->led,
>                                            gpio_data->desired_brightness);
>                 else
> -                       __led_set_brightness(gpio_data->led, LED_FULL);
> +                       led_set_brightness_async(gpio_data->led, LED_FULL);
>         } else {
> -               __led_set_brightness(gpio_data->led, LED_OFF);
> +               led_set_brightness_async(gpio_data->led, LED_OFF);
>         }
>  }
>
> diff --git a/drivers/leds/trigger/ledtrig-heartbeat.c b/drivers/leds/trigger/ledtrig-heartbeat.c
> index 5c8464a..fea6871 100644
> --- a/drivers/leds/trigger/ledtrig-heartbeat.c
> +++ b/drivers/leds/trigger/ledtrig-heartbeat.c
> @@ -74,7 +74,7 @@ static void led_heartbeat_function(unsigned long data)
>                 break;
>         }
>
> -       __led_set_brightness(led_cdev, brightness);
> +       led_set_brightness_async(led_cdev, brightness);
>         mod_timer(&heartbeat_data->timer, jiffies + delay);
>  }
>
> diff --git a/drivers/leds/trigger/ledtrig-oneshot.c b/drivers/leds/trigger/ledtrig-oneshot.c
> index cb4c746..fbd02cd 100644
> --- a/drivers/leds/trigger/ledtrig-oneshot.c
> +++ b/drivers/leds/trigger/ledtrig-oneshot.c
> @@ -63,9 +63,9 @@ static ssize_t led_invert_store(struct device *dev,
>         oneshot_data->invert = !!state;
>
>         if (oneshot_data->invert)
> -               __led_set_brightness(led_cdev, LED_FULL);
> +               led_set_brightness_async(led_cdev, LED_FULL);
>         else
> -               __led_set_brightness(led_cdev, LED_OFF);
> +               led_set_brightness_async(led_cdev, LED_OFF);
>
>         return size;
>  }
> diff --git a/drivers/leds/trigger/ledtrig-transient.c b/drivers/leds/trigger/ledtrig-transient.c
> index e5abc00..3c34de4 100644
> --- a/drivers/leds/trigger/ledtrig-transient.c
> +++ b/drivers/leds/trigger/ledtrig-transient.c
> @@ -41,7 +41,7 @@ static void transient_timer_function(unsigned long data)
>         struct transient_trig_data *transient_data = led_cdev->trigger_data;
>
>         transient_data->activate = 0;
> -       __led_set_brightness(led_cdev, transient_data->restore_state);
> +       led_set_brightness_async(led_cdev, transient_data->restore_state);
>  }
>
>  static ssize_t transient_activate_show(struct device *dev,
> @@ -72,7 +72,8 @@ static ssize_t transient_activate_store(struct device *dev,
>         if (state == 0 && transient_data->activate == 1) {
>                 del_timer(&transient_data->timer);
>                 transient_data->activate = state;
> -               __led_set_brightness(led_cdev, transient_data->restore_state);
> +               led_set_brightness_async(led_cdev,
> +                                       transient_data->restore_state);
>                 return size;
>         }
>
> @@ -80,7 +81,7 @@ static ssize_t transient_activate_store(struct device *dev,
>         if (state == 1 && transient_data->activate == 0 &&
>             transient_data->duration != 0) {
>                 transient_data->activate = state;
> -               __led_set_brightness(led_cdev, transient_data->state);
> +               led_set_brightness_async(led_cdev, transient_data->state);
>                 transient_data->restore_state =
>                     (transient_data->state == LED_FULL) ? LED_OFF : LED_FULL;
>                 mod_timer(&transient_data->timer,
> @@ -203,7 +204,8 @@ static void transient_trig_deactivate(struct led_classdev *led_cdev)
>
>         if (led_cdev->activated) {
>                 del_timer_sync(&transient_data->timer);
> -               __led_set_brightness(led_cdev, transient_data->restore_state);
> +               led_set_brightness_async(led_cdev,
> +                                       transient_data->restore_state);
>                 device_remove_file(led_cdev->dev, &dev_attr_activate);
>                 device_remove_file(led_cdev->dev, &dev_attr_duration);
>                 device_remove_file(led_cdev->dev, &dev_attr_state);
> diff --git a/include/linux/leds.h b/include/linux/leds.h
> index 3737a5a..cfceef3 100644
> --- a/include/linux/leds.h
> +++ b/include/linux/leds.h
> @@ -44,11 +44,19 @@ struct led_classdev {
>  #define LED_BLINK_ONESHOT_STOP (1 << 18)
>  #define LED_BLINK_INVERT       (1 << 19)
>  #define LED_SYSFS_DISABLE      (1 << 20)
> +#define SET_BRIGHTNESS_ASYNC   (1 << 21)
> +#define SET_BRIGHTNESS_SYNC    (1 << 22)
>
>         /* Set LED brightness level */
>         /* Must not sleep, use a workqueue if needed */
>         void            (*brightness_set)(struct led_classdev *led_cdev,
>                                           enum led_brightness brightness);
> +       /*
> +        * Set LED brightness level immediately - it can block the caller for
> +        * the time required for accessing a LED device register.
> +        */
> +       int             (*brightness_set_sync)(struct led_classdev *led_cdev,
> +                                       enum led_brightness brightness);
>         /* Get LED brightness level */
>         enum led_brightness (*brightness_get)(struct led_classdev *led_cdev);
>
> --
> 1.7.9.5
>
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diff mbox

Patch

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 65722de..dbeebac 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -55,7 +55,7 @@  static ssize_t brightness_store(struct device *dev,
 
 	if (state == LED_OFF)
 		led_trigger_remove(led_cdev);
-	__led_set_brightness(led_cdev, state);
+	led_set_brightness(led_cdev, state);
 
 	ret = size;
 unlock:
@@ -109,7 +109,7 @@  static void led_timer_function(unsigned long data)
 	unsigned long delay;
 
 	if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
-		__led_set_brightness(led_cdev, LED_OFF);
+		led_set_brightness_async(led_cdev, LED_OFF);
 		return;
 	}
 
@@ -132,7 +132,7 @@  static void led_timer_function(unsigned long data)
 		delay = led_cdev->blink_delay_off;
 	}
 
-	__led_set_brightness(led_cdev, brightness);
+	led_set_brightness_async(led_cdev, brightness);
 
 	/* Return in next iteration if led is in one-shot mode and we are in
 	 * the final blink state so that the led is toggled each delay_on +
@@ -158,7 +158,7 @@  static void set_brightness_delayed(struct work_struct *ws)
 
 	led_stop_software_blink(led_cdev);
 
-	__led_set_brightness(led_cdev, led_cdev->delayed_set_value);
+	led_set_brightness_async(led_cdev, led_cdev->delayed_set_value);
 }
 
 /**
@@ -233,6 +233,8 @@  int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
 	if (!led_cdev->max_brightness)
 		led_cdev->max_brightness = LED_FULL;
 
+	led_cdev->flags |= SET_BRIGHTNESS_ASYNC;
+
 	led_update_brightness(led_cdev);
 
 	INIT_WORK(&led_cdev->set_brightness_work, set_brightness_delayed);
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index be6d9fa..a745e32 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -42,13 +42,13 @@  static void led_set_software_blink(struct led_classdev *led_cdev,
 
 	/* never on - just set to off */
 	if (!delay_on) {
-		__led_set_brightness(led_cdev, LED_OFF);
+		led_set_brightness_async(led_cdev, LED_OFF);
 		return;
 	}
 
 	/* never off - just set to brightness */
 	if (!delay_off) {
-		__led_set_brightness(led_cdev, led_cdev->blink_brightness);
+		led_set_brightness_async(led_cdev, led_cdev->blink_brightness);
 		return;
 	}
 
@@ -117,6 +117,8 @@  EXPORT_SYMBOL_GPL(led_stop_software_blink);
 void led_set_brightness(struct led_classdev *led_cdev,
 			enum led_brightness brightness)
 {
+	int ret = 0;
+
 	/* delay brightness setting if need to stop soft-blink timer */
 	if (led_cdev->blink_delay_on || led_cdev->blink_delay_off) {
 		led_cdev->delayed_set_value = brightness;
@@ -124,7 +126,18 @@  void led_set_brightness(struct led_classdev *led_cdev,
 		return;
 	}
 
-	__led_set_brightness(led_cdev, brightness);
+	if (led_cdev->flags & SET_BRIGHTNESS_ASYNC) {
+		led_set_brightness_async(led_cdev, brightness);
+		return;
+	} else if (led_cdev->flags & SET_BRIGHTNESS_SYNC) {
+		ret = led_set_brightness_sync(led_cdev, brightness);
+	} else {
+		ret = -EINVAL;
+	}
+
+	if (ret < 0)
+		dev_dbg(led_cdev->dev, "Setting LED brightness failed (%d)\n",
+			ret);
 }
 EXPORT_SYMBOL(led_set_brightness);
 
diff --git a/drivers/leds/leds.h b/drivers/leds/leds.h
index 4c50365..2348dbd 100644
--- a/drivers/leds/leds.h
+++ b/drivers/leds/leds.h
@@ -17,16 +17,28 @@ 
 #include <linux/rwsem.h>
 #include <linux/leds.h>
 
-static inline void __led_set_brightness(struct led_classdev *led_cdev,
+static inline void led_set_brightness_async(struct led_classdev *led_cdev,
 					enum led_brightness value)
 {
-	if (value > led_cdev->max_brightness)
-		value = led_cdev->max_brightness;
-	led_cdev->brightness = value;
+	led_cdev->brightness = min(value, led_cdev->max_brightness);
+
 	if (!(led_cdev->flags & LED_SUSPENDED))
 		led_cdev->brightness_set(led_cdev, value);
 }
 
+static inline int led_set_brightness_sync(struct led_classdev *led_cdev,
+					enum led_brightness value)
+{
+	int ret = 0;
+
+	led_cdev->brightness = min(value, led_cdev->max_brightness);
+
+	if (!(led_cdev->flags & LED_SUSPENDED))
+		ret = led_cdev->brightness_set_sync(led_cdev,
+						led_cdev->brightness);
+	return ret;
+}
+
 static inline int led_get_brightness(struct led_classdev *led_cdev)
 {
 	return led_cdev->brightness;
diff --git a/drivers/leds/trigger/ledtrig-backlight.c b/drivers/leds/trigger/ledtrig-backlight.c
index 47e55aa..59eca17 100644
--- a/drivers/leds/trigger/ledtrig-backlight.c
+++ b/drivers/leds/trigger/ledtrig-backlight.c
@@ -51,9 +51,9 @@  static int fb_notifier_callback(struct notifier_block *p,
 
 	if ((n->old_status == UNBLANK) ^ n->invert) {
 		n->brightness = led->brightness;
-		__led_set_brightness(led, LED_OFF);
+		led_set_brightness_async(led, LED_OFF);
 	} else {
-		__led_set_brightness(led, n->brightness);
+		led_set_brightness_async(led, n->brightness);
 	}
 
 	n->old_status = new_status;
@@ -89,9 +89,9 @@  static ssize_t bl_trig_invert_store(struct device *dev,
 
 	/* After inverting, we need to update the LED. */
 	if ((n->old_status == BLANK) ^ n->invert)
-		__led_set_brightness(led, LED_OFF);
+		led_set_brightness_async(led, LED_OFF);
 	else
-		__led_set_brightness(led, n->brightness);
+		led_set_brightness_async(led, n->brightness);
 
 	return num;
 }
diff --git a/drivers/leds/trigger/ledtrig-default-on.c b/drivers/leds/trigger/ledtrig-default-on.c
index 81a91be..6f38f88 100644
--- a/drivers/leds/trigger/ledtrig-default-on.c
+++ b/drivers/leds/trigger/ledtrig-default-on.c
@@ -19,7 +19,7 @@ 
 
 static void defon_trig_activate(struct led_classdev *led_cdev)
 {
-	__led_set_brightness(led_cdev, led_cdev->max_brightness);
+	led_set_brightness_async(led_cdev, led_cdev->max_brightness);
 }
 
 static struct led_trigger defon_led_trigger = {
diff --git a/drivers/leds/trigger/ledtrig-gpio.c b/drivers/leds/trigger/ledtrig-gpio.c
index c86c418..4cc7040 100644
--- a/drivers/leds/trigger/ledtrig-gpio.c
+++ b/drivers/leds/trigger/ledtrig-gpio.c
@@ -54,12 +54,12 @@  static void gpio_trig_work(struct work_struct *work)
 
 	if (tmp) {
 		if (gpio_data->desired_brightness)
-			__led_set_brightness(gpio_data->led,
+			led_set_brightness_async(gpio_data->led,
 					   gpio_data->desired_brightness);
 		else
-			__led_set_brightness(gpio_data->led, LED_FULL);
+			led_set_brightness_async(gpio_data->led, LED_FULL);
 	} else {
-		__led_set_brightness(gpio_data->led, LED_OFF);
+		led_set_brightness_async(gpio_data->led, LED_OFF);
 	}
 }
 
diff --git a/drivers/leds/trigger/ledtrig-heartbeat.c b/drivers/leds/trigger/ledtrig-heartbeat.c
index 5c8464a..fea6871 100644
--- a/drivers/leds/trigger/ledtrig-heartbeat.c
+++ b/drivers/leds/trigger/ledtrig-heartbeat.c
@@ -74,7 +74,7 @@  static void led_heartbeat_function(unsigned long data)
 		break;
 	}
 
-	__led_set_brightness(led_cdev, brightness);
+	led_set_brightness_async(led_cdev, brightness);
 	mod_timer(&heartbeat_data->timer, jiffies + delay);
 }
 
diff --git a/drivers/leds/trigger/ledtrig-oneshot.c b/drivers/leds/trigger/ledtrig-oneshot.c
index cb4c746..fbd02cd 100644
--- a/drivers/leds/trigger/ledtrig-oneshot.c
+++ b/drivers/leds/trigger/ledtrig-oneshot.c
@@ -63,9 +63,9 @@  static ssize_t led_invert_store(struct device *dev,
 	oneshot_data->invert = !!state;
 
 	if (oneshot_data->invert)
-		__led_set_brightness(led_cdev, LED_FULL);
+		led_set_brightness_async(led_cdev, LED_FULL);
 	else
-		__led_set_brightness(led_cdev, LED_OFF);
+		led_set_brightness_async(led_cdev, LED_OFF);
 
 	return size;
 }
diff --git a/drivers/leds/trigger/ledtrig-transient.c b/drivers/leds/trigger/ledtrig-transient.c
index e5abc00..3c34de4 100644
--- a/drivers/leds/trigger/ledtrig-transient.c
+++ b/drivers/leds/trigger/ledtrig-transient.c
@@ -41,7 +41,7 @@  static void transient_timer_function(unsigned long data)
 	struct transient_trig_data *transient_data = led_cdev->trigger_data;
 
 	transient_data->activate = 0;
-	__led_set_brightness(led_cdev, transient_data->restore_state);
+	led_set_brightness_async(led_cdev, transient_data->restore_state);
 }
 
 static ssize_t transient_activate_show(struct device *dev,
@@ -72,7 +72,8 @@  static ssize_t transient_activate_store(struct device *dev,
 	if (state == 0 && transient_data->activate == 1) {
 		del_timer(&transient_data->timer);
 		transient_data->activate = state;
-		__led_set_brightness(led_cdev, transient_data->restore_state);
+		led_set_brightness_async(led_cdev,
+					transient_data->restore_state);
 		return size;
 	}
 
@@ -80,7 +81,7 @@  static ssize_t transient_activate_store(struct device *dev,
 	if (state == 1 && transient_data->activate == 0 &&
 	    transient_data->duration != 0) {
 		transient_data->activate = state;
-		__led_set_brightness(led_cdev, transient_data->state);
+		led_set_brightness_async(led_cdev, transient_data->state);
 		transient_data->restore_state =
 		    (transient_data->state == LED_FULL) ? LED_OFF : LED_FULL;
 		mod_timer(&transient_data->timer,
@@ -203,7 +204,8 @@  static void transient_trig_deactivate(struct led_classdev *led_cdev)
 
 	if (led_cdev->activated) {
 		del_timer_sync(&transient_data->timer);
-		__led_set_brightness(led_cdev, transient_data->restore_state);
+		led_set_brightness_async(led_cdev,
+					transient_data->restore_state);
 		device_remove_file(led_cdev->dev, &dev_attr_activate);
 		device_remove_file(led_cdev->dev, &dev_attr_duration);
 		device_remove_file(led_cdev->dev, &dev_attr_state);
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 3737a5a..cfceef3 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -44,11 +44,19 @@  struct led_classdev {
 #define LED_BLINK_ONESHOT_STOP	(1 << 18)
 #define LED_BLINK_INVERT	(1 << 19)
 #define LED_SYSFS_DISABLE	(1 << 20)
+#define SET_BRIGHTNESS_ASYNC	(1 << 21)
+#define SET_BRIGHTNESS_SYNC	(1 << 22)
 
 	/* Set LED brightness level */
 	/* Must not sleep, use a workqueue if needed */
 	void		(*brightness_set)(struct led_classdev *led_cdev,
 					  enum led_brightness brightness);
+	/*
+	 * Set LED brightness level immediately - it can block the caller for
+	 * the time required for accessing a LED device register.
+	 */
+	int		(*brightness_set_sync)(struct led_classdev *led_cdev,
+					enum led_brightness brightness);
 	/* Get LED brightness level */
 	enum led_brightness (*brightness_get)(struct led_classdev *led_cdev);