[PATCH 2/5] backlight: pwm_bl: eliminate a 64/32 division
Rasmus Villemoes
linux at rasmusvillemoes.dk
Thu Sep 19 14:06:17 UTC 2019
lightness*1000 is nowhere near overflowing 32 bits, so we can just use
an ordinary 32/32 division, which is much cheaper than the 64/32 done
via do_div().
Signed-off-by: Rasmus Villemoes <linux at rasmusvillemoes.dk>
---
drivers/video/backlight/pwm_bl.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index be36be1cacb7..9252d51f31b9 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -177,7 +177,7 @@ static u64 cie1931(unsigned int lightness, unsigned int scale)
*/
lightness *= 100;
if (lightness <= (8 * scale)) {
- retval = DIV_ROUND_CLOSEST_ULL(lightness * 10, 9033);
+ retval = DIV_ROUND_CLOSEST(lightness * 10, 9033);
} else {
retval = int_pow((lightness + (16 * scale)) / 116, 3);
retval = DIV_ROUND_CLOSEST_ULL(retval, (scale * scale));
--
2.20.1
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