backlight: Avoid unecessary driver callbacks

Avoid driver callbacks when the brightness hasn't changed since
they're not necessary.

Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>

1 files changed, 8 insertions, 4 deletions

diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index 4840fe217e4d..39394757679c 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -94,8 +94,10 @@ static ssize_t backlight_store_power(struct device *dev,
         mutex_lock(&bd->ops_lock);
         if (bd->ops) {
                 pr_debug("backlight: set power to %d\n", power);
-                bd->props.power = power;
-                backlight_update_status(bd);
+                if (bd->props.power != power) {
+                        bd->props.power = power;
+                        backlight_update_status(bd);
+                }
                 rc = count;
         }
         mutex_unlock(&bd->ops_lock);
@@ -132,8 +134,10 @@ static ssize_t backlight_store_brightness(struct device *dev,
                 else {
                         pr_debug("backlight: set brightness to %d\n",
                                  brightness);
-                        bd->props.brightness = brightness;
-                        backlight_update_status(bd);
+                        if (bd->props.brightness != brightness) {
+                                bd->props.brightness = brightness;
+                                backlight_update_status(bd);
+                        }
                         rc = count;
                 }
         }