From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rasmus Villemoes Subject: [PATCH v2 2/4] backlight: pwm_bl: eliminate a 64/32 division Date: Tue, 8 Oct 2019 14:03:25 +0200 Message-ID: <20191008120327.24208-3-linux@rasmusvillemoes.dk> References: <20191008120327.24208-1-linux@rasmusvillemoes.dk> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20191008120327.24208-1-linux@rasmusvillemoes.dk> Sender: linux-kernel-owner@vger.kernel.org To: Thierry Reding , =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= , Lee Jones , Daniel Thompson , Jingoo Han , Bartlomiej Zolnierkiewicz Cc: Rasmus Villemoes , linux-pwm@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-pwm@vger.kernel.org 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(). Reviewed-by: Daniel Thompson Signed-off-by: Rasmus Villemoes --- 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 cc44a02e95c7..672c5e7cfcd1 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