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From:   Nylon Chen <nylon.chen@sifive.com>
To:     paul.walmsley@sifive.com, palmer@dabbelt.com,
        linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org
Cc:     nylon7717@gmail.com, zong.li@sifive.com, greentime.hu@sifive.com,
        vincent.chen@sifive.com, Nylon Chen <nylon.chen@sifive.com>
Subject: [PATCH 2/2] pwm: sifive: change the PWM controlled LED algorithm
Date:   Fri, 13 Jan 2023 16:31:15 +0800
Message-Id: <20230113083115.2590-3-nylon.chen@sifive.com>
In-Reply-To: <20230113083115.2590-1-nylon.chen@sifive.com>
References: <20230113083115.2590-1-nylon.chen@sifive.com>
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The `frac` variable represents the pulse inactive time, and the result of
this algorithm is the pulse active time. Therefore, we must reverse the
result.

Signed-off-by: Nylon Chen <nylon.chen@sifive.com>
Reviewed-by: Vincent Chen <vincent.chen@sifive.com>
---
 drivers/pwm/pwm-sifive.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c
index 62b6acc6373d..a5eda165d071 100644
--- a/drivers/pwm/pwm-sifive.c
+++ b/drivers/pwm/pwm-sifive.c
@@ -158,6 +158,7 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	frac = DIV64_U64_ROUND_CLOSEST(num, state->period);
 	/* The hardware cannot generate a 100% duty cycle */
 	frac = min(frac, (1U << PWM_SIFIVE_CMPWIDTH) - 1);
+	frac = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - frac;
 
 	mutex_lock(&ddata->lock);
 	if (state->period != ddata->approx_period) {
-- 
2.36.1