linux-kernel - [PATCH V2 3/6] pwm: sprd: Optimize the calculation method of duty

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20240125025533.10315-4-Wenhua.Lin@unisoc.com>
Date: Thu, 25 Jan 2024 10:55:30 +0800
From: Wenhua Lin <Wenhua.Lin@...soc.com>
To: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
        Rob
 Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski
	<krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>
CC: Orson Zhai <orsonzhai@...il.com>,
        Baolin Wang
	<baolin.wang@...ux.alibaba.com>,
        Chunyan Zhang <zhang.lyra@...il.com>, <linux-pwm@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        wenhua lin <wenhua.lin1994@...il.com>,
        Wenhua
 Lin <Wenhua.Lin@...soc.com>,
        Xiongpeng Wu <xiongpeng.wu@...soc.com>,
        zhaochen
 su <zhaochen.su29@...il.com>,
        Zhaochen Su <Zhaochen.Su@...soc.com>,
        Xiaolong
 Wang <Xiaolong.Wang@...soc.com>
Subject: [PATCH V2 3/6] pwm: sprd: Optimize the calculation method of duty

Use DIV_ROUND_CLOSEST_ULL to avoid overflow and improve accuracy
when calculating duty.

Signed-off-by: Wenhua Lin <Wenhua.Lin@...soc.com>
---
 drivers/pwm/pwm-sprd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/pwm/pwm-sprd.c b/drivers/pwm/pwm-sprd.c
index cc54aa77c7e6..8de3f9e154ce 100644
--- a/drivers/pwm/pwm-sprd.c
+++ b/drivers/pwm/pwm-sprd.c
@@ -156,7 +156,8 @@ static int sprd_pwm_config(struct sprd_pwm_chip *spc, struct pwm_device *pwm,
 	 * given settings (MOD and input clock).
 	 */
 	mod = spc->mod[pwm->hwpwm];
-	duty = duty_ns * mod / period_ns;
+	tmp = (u64)duty_ns * mod;
+	duty = DIV_ROUND_CLOSEST_ULL(tmp, period_ns);
 
 	tmp = (u64)chn->clk_rate * period_ns;
 	do_div(tmp, NSEC_PER_SEC);
-- 
2.17.1