1 files changed, 22 insertions, 9 deletions

diff --git a/arch/powerpc/platforms/powermac/backlight.c b/arch/powerpc/platforms/powermac/backlight.c
index 69f65e215a5c..74eed6b74cd6 100644
--- a/arch/powerpc/platforms/powermac/backlight.c
+++ b/arch/powerpc/platforms/powermac/backlight.c
@@ -15,6 +15,15 @@
 
 #define OLD_BACKLIGHT_MAX 15
 
+static void pmac_backlight_key_worker(void *data);
+static DECLARE_WORK(pmac_backlight_key_work, pmac_backlight_key_worker, NULL);
+
+/* Although this variable is used in interrupt context, it makes no sense to
+ * protect it. No user is able to produce enough key events per second and
+ * notice the errors that might happen.
+ */
+static int pmac_backlight_key_queued;
+
 /* Protect the pmac_backlight variable */
 DEFINE_MUTEX(pmac_backlight_mutex);
 
@@ -71,7 +80,7 @@ int pmac_backlight_curve_lookup(struct fb_info *info, int value)
         return level;
 }
 
-static void pmac_backlight_key(int direction)
+static void pmac_backlight_key_worker(void *data)
 {
         mutex_lock(&pmac_backlight_mutex);
         if (pmac_backlight) {
@@ -82,7 +91,8 @@ static void pmac_backlight_key(int direction)
                 props = pmac_backlight->props;
 
                 brightness = props->brightness +
-                        ((direction?-1:1) * (props->max_brightness / 15));
+                        ((pmac_backlight_key_queued?-1:1) *
+                         (props->max_brightness / 15));
 
                 if (brightness < 0)
                         brightness = 0;
@@ -97,14 +107,13 @@ static void pmac_backlight_key(int direction)
         mutex_unlock(&pmac_backlight_mutex);
 }
 
-void pmac_backlight_key_up()
+void pmac_backlight_key(int direction)
 {
-        pmac_backlight_key(0);
-}
-
-void pmac_backlight_key_down()
-{
-        pmac_backlight_key(1);
+        /* we can receive multiple interrupts here, but the scheduled work
+         * will run only once, with the last value
+         */
+        pmac_backlight_key_queued = direction;
+        schedule_work(&pmac_backlight_key_work);
 }
 
 int pmac_backlight_set_legacy_brightness(int brightness)
@@ -157,3 +166,7 @@ int pmac_backlight_get_legacy_brightness()
 
         return result;
 }
+
+EXPORT_SYMBOL_GPL(pmac_backlight);
+EXPORT_SYMBOL_GPL(pmac_backlight_mutex);
+EXPORT_SYMBOL_GPL(pmac_has_backlight_type);