leds: delay led_set_brightness if stopping soft-blink

Delay execution of led_set_brightness() if need to stop soft-blink
timer.

This allows led_set_brightness to be called in hard-irq context even if
soft-blink was activated on that LED.

Signed-off-by: Fabio Baltieri <fabio.baltieri@gmail.com>
Cc: Pawel Moll <pawel.moll@arm.com>
Signed-off-by: Bryan Wu <bryan.wu@canonical.com>

drivers/leds/led-class.c

@@ -124,6 +124,16 @@ static void led_timer_function(unsigned long data)
 	mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay));
 }
 
+static void set_brightness_delayed(struct work_struct *ws)
+{
+	struct led_classdev *led_cdev =
+		container_of(ws, struct led_classdev, set_brightness_work);
+
+	led_stop_software_blink(led_cdev);
+
+	__led_set_brightness(led_cdev, led_cdev->delayed_set_value);
+}
+
 /**
  * led_classdev_suspend - suspend an led_classdev.
  * @led_cdev: the led_classdev to suspend.
@@ -191,6 +201,8 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
 
 	led_update_brightness(led_cdev);
 
+	INIT_WORK(&led_cdev->set_brightness_work, set_brightness_delayed);
+
 	init_timer(&led_cdev->blink_timer);
 	led_cdev->blink_timer.function = led_timer_function;
 	led_cdev->blink_timer.data = (unsigned long)led_cdev;
@@ -221,7 +233,10 @@ void led_classdev_unregister(struct led_classdev *led_cdev)
 	up_write(&led_cdev->trigger_lock);
 #endif
 
+	cancel_work_sync(&led_cdev->set_brightness_work);
+
 	/* Stop blinking */
+	led_stop_software_blink(led_cdev);
 	led_set_brightness(led_cdev, LED_OFF);
 
 	device_unregister(led_cdev->dev);

drivers/leds/led-core.c

@@ -103,13 +103,23 @@ void led_blink_set_oneshot(struct led_classdev *led_cdev,
 }
 EXPORT_SYMBOL(led_blink_set_oneshot);
 
-void led_set_brightness(struct led_classdev *led_cdev,
-			enum led_brightness brightness)
+void led_stop_software_blink(struct led_classdev *led_cdev)
 {
-	/* stop and clear soft-blink timer */
 	del_timer_sync(&led_cdev->blink_timer);
 	led_cdev->blink_delay_on = 0;
 	led_cdev->blink_delay_off = 0;
+}
+EXPORT_SYMBOL_GPL(led_stop_software_blink);
+
+void led_set_brightness(struct led_classdev *led_cdev,
+			enum led_brightness brightness)
+{
+	/* 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;
+		schedule_work(&led_cdev->set_brightness_work);
+		return;
+	}
 
 	__led_set_brightness(led_cdev, brightness);
 }

drivers/leds/led-triggers.c

@@ -109,6 +109,8 @@ void led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig)
 		list_del(&led_cdev->trig_list);
 		write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock,
 			flags);
+		cancel_work_sync(&led_cdev->set_brightness_work);
+		led_stop_software_blink(led_cdev);
 		if (led_cdev->trigger->deactivate)
 			led_cdev->trigger->deactivate(led_cdev);
 		led_cdev->trigger = NULL;
@@ -224,7 +226,7 @@ void led_trigger_event(struct led_trigger *trig,
 		struct led_classdev *led_cdev;
 
 		led_cdev = list_entry(entry, struct led_classdev, trig_list);
-		__led_set_brightness(led_cdev, brightness);
+		led_set_brightness(led_cdev, brightness);
 	}
 	read_unlock(&trig->leddev_list_lock);
 }

drivers/leds/leds.h

@@ -32,6 +32,8 @@ static inline int led_get_brightness(struct led_classdev *led_cdev)
 	return led_cdev->brightness;
 }
 
+void led_stop_software_blink(struct led_classdev *led_cdev);
+
 extern struct rw_semaphore leds_list_lock;
 extern struct list_head leds_list;
 

include/linux/leds.h

@@ -16,6 +16,7 @@
 #include <linux/spinlock.h>
 #include <linux/rwsem.h>
 #include <linux/timer.h>
+#include <linux/workqueue.h>
 
 struct device;
 /*
@@ -69,6 +70,9 @@ struct led_classdev {
 	struct timer_list	 blink_timer;
 	int			 blink_brightness;
 
+	struct work_struct	set_brightness_work;
+	int			delayed_set_value;
+
 #ifdef CONFIG_LEDS_TRIGGERS
 	/* Protects the trigger data below */
 	struct rw_semaphore	 trigger_lock;