leds: fix led_brightness_set when soft-blinking

Move led_stop_software_blink() code into led_brightness_set() to ensure
software blink timer is stopped and cleared when changing trigger.

Also use led_set_brightness() instead of calling
led_cdev->brightness_set() directly to keep led_cdev->brightness
consistent with current LED status.

This ensure proper cleaning when changing triggers, as without this fix
a LED may be turned off while leaving it's led_cdev->brightness = 1,
leading to an erratic software-blink behaviour.

The problem was easy to reproduce by changing the trigger from "timer"
to "oneshot".

Signed-off-by: Fabio Baltieri <fabio.baltieri@gmail.com>
Signed-off-by: Bryan Wu <bryan.wu@canonical.com>

drivers/leds/led-core.c

@@ -24,13 +24,6 @@ EXPORT_SYMBOL_GPL(leds_list_lock);
 LIST_HEAD(leds_list);
 EXPORT_SYMBOL_GPL(leds_list);
 
-static void led_stop_software_blink(struct led_classdev *led_cdev)
-{
-	/* deactivate previous settings */
-	led_cdev->blink_delay_on = 0;
-	led_cdev->blink_delay_off = 0;
-}
-
 static void led_set_software_blink(struct led_classdev *led_cdev,
 				   unsigned long delay_on,
 				   unsigned long delay_off)
@@ -113,7 +106,11 @@ EXPORT_SYMBOL(led_blink_set_oneshot);
 void led_brightness_set(struct led_classdev *led_cdev,
 			enum led_brightness brightness)
 {
-	led_stop_software_blink(led_cdev);
-	led_cdev->brightness_set(led_cdev, brightness);
+	/* 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;
+
+	led_set_brightness(led_cdev, brightness);
 }
 EXPORT_SYMBOL(led_brightness_set);