From 407feae1cacaa5d00ebe686532a73ad6de747409 Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Tue, 8 Oct 2019 14:03:26 +0200 Subject: [PATCH] backlight: pwm_bl: Drop use of int_pow() For a fixed small exponent of 3, it is more efficient to simply use two explicit multiplications rather than calling the int_pow() library function: Aside from the function call overhead, its implementation using repeated squaring means it ends up doing four 64x64 multiplications. Signed-off-by: Rasmus Villemoes Reviewed-by: Daniel Thompson Signed-off-by: Lee Jones --- drivers/video/backlight/pwm_bl.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c index 15d84da77ecd..ee85055146dd 100644 --- a/drivers/video/backlight/pwm_bl.c +++ b/drivers/video/backlight/pwm_bl.c @@ -180,7 +180,8 @@ static u64 cie1931(unsigned int lightness, unsigned int scale) if (lightness <= (8 * scale)) { retval = DIV_ROUND_CLOSEST(lightness * 10, 9033); } else { - retval = int_pow((lightness + (16 * scale)) / 116, 3); + retval = (lightness + (16 * scale)) / 116; + retval *= retval * retval; retval = DIV_ROUND_CLOSEST_ULL(retval, (scale * scale)); } -- 2.39.5