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From: Wenhua Lin <Wenhua.Lin@unisoc.com>
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CC: Orson Zhai <orsonzhai@gmail.com>,
        Baolin Wang
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        Chunyan Zhang <zhang.lyra@gmail.com>, <linux-pwm@vger.kernel.org>,
        <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        wenhua lin <wenhua.lin1994@gmail.com>,
        Wenhua
 Lin <Wenhua.Lin@unisoc.com>,
        Xiongpeng Wu <xiongpeng.wu@unisoc.com>,
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        Zhaochen Su <Zhaochen.Su@unisoc.com>,
        Xiaolong
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Subject: [PATCH V2 3/6] pwm: sprd: Optimize the calculation method of duty
Date: Thu, 25 Jan 2024 10:55:30 +0800
Message-ID: <20240125025533.10315-4-Wenhua.Lin@unisoc.com>
In-Reply-To: <20240125025533.10315-1-Wenhua.Lin@unisoc.com>
References: <20240125025533.10315-1-Wenhua.Lin@unisoc.com>
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Use DIV_ROUND_CLOSEST_ULL to avoid overflow and improve accuracy
when calculating duty.

Signed-off-by: Wenhua Lin <Wenhua.Lin@unisoc.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