leds: disable triggers on brightness set

Disable any active triggers when the brightness attribute is
set to zero.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Márton Németh <nm127@freemail.hu>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>

5 files changed, 47 insertions, 10 deletions

diff --git a/Documentation/leds-class.txt b/Documentation/leds-class.txt
index 56757c751d6f..18860ad9935a 100644
--- a/Documentation/leds-class.txt
+++ b/Documentation/leds-class.txt
@@ -19,6 +19,12 @@ optimises away.
 
 Complex triggers whilst available to all LEDs have LED specific
 parameters and work on a per LED basis. The timer trigger is an example.
+The timer trigger will periodically change the LED brightness between
+LED_OFF and the current brightness setting. The "on" and "off" time can
+be specified via /sys/class/leds/<device>/delay_{on,off} in milliseconds.
+You can change the brightness value of a LED independently of the timer
+trigger. However, if you set the brightness value to LED_OFF it will
+also disable the timer trigger.
 
 You can change triggers in a similar manner to the way an IO scheduler
 is chosen (via /sys/class/leds/<device>/trigger). Trigger specific
@@ -63,9 +69,9 @@ value if it is called with *delay_on==0 && *delay_off==0 parameters. In
 this case the driver should give back the chosen value through delay_on
 and delay_off parameters to the leds subsystem.
 
-Any call to the brightness_set() callback function should cancel the
-previously programmed hardware blinking function so setting the brightness
-to 0 can also cancel the blinking of the LED.
+Setting the brightness to zero with brightness_set() callback function
+should completely turn off the LED and cancel the previously programmed
+hardware blinking function, if any.
 
 
 Known Issues
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 63aad90247c4..a8dd59ebedf8 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -51,6 +51,9 @@ static ssize_t led_brightness_store(struct device *dev,
 
         if (count == size) {
                 ret = count;
+
+                if (state == LED_OFF)
+                        led_trigger_remove(led_cdev);
                 led_set_brightness(led_cdev, state);
         }
 
diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
index 13c9026d68af..21dd96909444 100644
--- a/drivers/leds/led-triggers.c
+++ b/drivers/leds/led-triggers.c
@@ -45,9 +45,7 @@ ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
                 trigger_name[len - 1] = '\0';
 
         if (!strcmp(trigger_name, "none")) {
-                down_write(&led_cdev->trigger_lock);
-                led_trigger_set(led_cdev, NULL);
-                up_write(&led_cdev->trigger_lock);
+                led_trigger_remove(led_cdev);
                 return count;
         }
 
@@ -139,6 +137,13 @@ void led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trigger)
         led_cdev->trigger = trigger;
 }
 
+void led_trigger_remove(struct led_classdev *led_cdev)
+{
+        down_write(&led_cdev->trigger_lock);
+        led_trigger_set(led_cdev, NULL);
+        up_write(&led_cdev->trigger_lock);
+}
+
 void led_trigger_set_default(struct led_classdev *led_cdev)
 {
         struct led_trigger *trig;
@@ -231,6 +236,7 @@ void led_trigger_unregister_simple(struct led_trigger *trigger)
 
 /* Used by LED Class */
 EXPORT_SYMBOL_GPL(led_trigger_set);
+EXPORT_SYMBOL_GPL(led_trigger_remove);
 EXPORT_SYMBOL_GPL(led_trigger_set_default);
 EXPORT_SYMBOL_GPL(led_trigger_show);
 EXPORT_SYMBOL_GPL(led_trigger_store);
diff --git a/drivers/leds/leds.h b/drivers/leds/leds.h
index 12b6fe93b135..0214799639f7 100644
--- a/drivers/leds/leds.h
+++ b/drivers/leds/leds.h
@@ -27,6 +27,11 @@ static inline void led_set_brightness(struct led_classdev *led_cdev,
                 led_cdev->brightness_set(led_cdev, value);
 }
 
+static inline int led_get_brightness(struct led_classdev *led_cdev)
+{
+        return led_cdev->brightness;
+}
+
 extern struct rw_semaphore leds_list_lock;
 extern struct list_head leds_list;
 
@@ -34,9 +39,11 @@ extern struct list_head leds_list;
 void led_trigger_set_default(struct led_classdev *led_cdev);
 void led_trigger_set(struct led_classdev *led_cdev,
                         struct led_trigger *trigger);
+void led_trigger_remove(struct led_classdev *led_cdev);
 #else
 #define led_trigger_set_default(x) do {} while(0)
 #define led_trigger_set(x, y) do {} while(0)
+#define led_trigger_remove(x) do {} while(0)
 #endif
 
 ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
diff --git a/drivers/leds/ledtrig-timer.c b/drivers/leds/ledtrig-timer.c
index 82c55d6e4902..706297765d93 100644
--- a/drivers/leds/ledtrig-timer.c
+++ b/drivers/leds/ledtrig-timer.c
@@ -25,6 +25,9 @@
 #include "leds.h"
 
 struct timer_trig_data {
+        int brightness_on;              /* LED brightness during "on" period.
+                                         * (LED_OFF < brightness_on <= LED_FULL)
+                                         */
         unsigned long delay_on;         /* milliseconds on */
         unsigned long delay_off;        /* milliseconds off */
         struct timer_list timer;
@@ -34,17 +37,26 @@ static void led_timer_function(unsigned long data)
 {
         struct led_classdev *led_cdev = (struct led_classdev *) data;
         struct timer_trig_data *timer_data = led_cdev->trigger_data;
-        unsigned long brightness = LED_OFF;
-        unsigned long delay = timer_data->delay_off;
+        unsigned long brightness;
+        unsigned long delay;
 
         if (!timer_data->delay_on || !timer_data->delay_off) {
                 led_set_brightness(led_cdev, LED_OFF);
                 return;
         }
 
-        if (!led_cdev->brightness) {
-                brightness = LED_FULL;
+        brightness = led_get_brightness(led_cdev);
+        if (!brightness) {
+                /* Time to switch the LED on. */
+                brightness = timer_data->brightness_on;
                 delay = timer_data->delay_on;
+        } else {
+                /* Store the current brightness value to be able
+                 * to restore it when the delay_off period is over.
+                 */
+                timer_data->brightness_on = brightness;
+                brightness = LED_OFF;
+                delay = timer_data->delay_off;
         }
 
         led_set_brightness(led_cdev, brightness);
@@ -156,6 +168,9 @@ static void timer_trig_activate(struct led_classdev *led_cdev)
         if (!timer_data)
                 return;
 
+        timer_data->brightness_on = led_get_brightness(led_cdev);
+        if (timer_data->brightness_on == LED_OFF)
+                timer_data->brightness_on = LED_FULL;
         led_cdev->trigger_data = timer_data;
 
         init_timer(&timer_data->timer);