From: Nylon Chen <nylon.chen@sifive.com>
To: aou@eecs.berkeley.edu, conor@kernel.org,
emil.renner.berthing@canonical.com, geert+renesas@glider.be,
heiko@sntech.de, krzysztof.kozlowski+dt@linaro.org,
palmer@dabbelt.com, paul.walmsley@sifive.com, robh+dt@kernel.org,
thierry.reding@gmail.com, u.kleine-koenig@pengutronix.de,
devicetree@vger.kernel.org, linux-pwm@vger.kernel.org,
linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Cc: nylon.chen@sifive.com, nylon7717@gmail.com, zong.li@sifive.com,
greentime.hu@sifive.com, vincent.chen@sifive.com
Subject: [PATCH v2 2/2] pwm: sifive: change the PWM controlled LED algorithm
Date: Mon, 30 Jan 2023 17:32:29 +0800 [thread overview]
Message-ID: <20230130093229.27489-3-nylon.chen@sifive.com> (raw)
In-Reply-To: <20230130093229.27489-1-nylon.chen@sifive.com>
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.
The reference is SiFive FU740-C000 Manual[0].
[0]: https://sifive.cdn.prismic.io/sifive/1a82e600-1f93-4f41-b2d8-86ed8b16acba_fu740-c000-manual-v1p6.pdf
Signed-off-by: Nylon Chen <nylon.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
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next prev parent reply other threads:[~2023-01-30 9:33 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-30 9:32 [PATCH v2 0/2] Change PWM-controlled LED pin active mode and algorithm Nylon Chen
2023-01-30 9:32 ` [PATCH v2 1/2] riscv: dts: sifive: unleashed/unmatched: Remove PWM controlled LED's active-low properties Nylon Chen
2023-01-31 18:31 ` Conor Dooley
2023-02-01 8:59 ` Nylon Chen
2023-01-30 9:32 ` Nylon Chen [this message]
2023-01-30 9:53 ` [PATCH v2 2/2] pwm: sifive: change the PWM controlled LED algorithm Geert Uytterhoeven
2023-02-01 8:51 ` Nylon Chen
2023-01-30 10:17 ` Uwe Kleine-König
2023-02-01 8:56 ` Nylon Chen
2023-03-01 9:20 ` Uwe Kleine-König
2023-03-02 10:41 ` Nylon Chen
2023-02-03 8:06 ` Nylon Chen
2023-02-21 5:54 ` Nylon Chen
2023-09-08 10:41 ` Nylon Chen
2023-09-08 14:49 ` Uwe Kleine-König
2023-09-10 13:16 ` Nylon Chen
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