[PATCH] powermac backlight fixes
Fix a erroneous calculation of the legacy brightness values as reported by
Paul Collins. Additionally, it moves the calculation of the negative value
in the radeonfb driver after the value check.
Signed-off-by: Michael Hanselmann <linux-kernel@hansmi.ch>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Paul Collins <paul@briny.ondioline.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/powerpc/platforms/powermac/backlight.c b/arch/powerpc/platforms/powermac/backlight.c
index 498b042..c7a27ed 100644
--- a/arch/powerpc/platforms/powermac/backlight.c
+++ b/arch/powerpc/platforms/powermac/backlight.c
@@ -119,7 +119,14 @@
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 @@
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);