1 files changed, 12 insertions, 2 deletions

diff --git a/arch/powerpc/platforms/powermac/backlight.c b/arch/powerpc/platforms/powermac/backlight.c
index 498b042e1837..c7a27eddca6d 100644
--- a/arch/powerpc/platforms/powermac/backlight.c
+++ b/arch/powerpc/platforms/powermac/backlight.c
@@ -119,7 +119,14 @@ int pmac_backlight_set_legacy_brightness(int brightness)
                 down(&pmac_backlight->sem);
                 props = pmac_backlight->props;
                 props->brightness = brightness *
-                        props->max_brightness / OLD_BACKLIGHT_MAX;
+                        (props->max_brightness + 1) /
+                        (OLD_BACKLIGHT_MAX + 1);
+
+                if (props->brightness > props->max_brightness)
+                        props->brightness = props->max_brightness;
+                else if (props->brightness < 0)
+                        props->brightness = 0;
+
                 props->update_status(pmac_backlight);
                 up(&pmac_backlight->sem);
 
@@ -140,8 +147,11 @@ int pmac_backlight_get_legacy_brightness()
 
                 down(&pmac_backlight->sem);
                 props = pmac_backlight->props;
+
                 result = props->brightness *
-                        OLD_BACKLIGHT_MAX / props->max_brightness;
+                        (OLD_BACKLIGHT_MAX + 1) /
+                        (props->max_brightness + 1);
+
                 up(&pmac_backlight->sem);
         }
         mutex_unlock(&pmac_backlight_mutex);