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From: Baruch Siach <baruch@tkos.co.il>
To: "Thierry Reding" <thierry.reding@gmail.com>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"Lee Jones" <lee.jones@linaro.org>,
	"Linus Walleij" <linus.walleij@linaro.org>,
	"Bartosz Golaszewski" <bgolaszewski@baylibre.com>
Cc: Baruch Siach <baruch@tkos.co.il>, Andrew Lunn <andrew@lunn.ch>,
	Gregory Clement <gregory.clement@bootlin.com>,
	Russell King <linux@armlinux.org.uk>,
	Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	Chris Packham <chris.packham@alliedtelesis.co.nz>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Ralph Sennhauser <ralph.sennhauser@gmail.com>,
	linux-pwm@vger.kernel.org, linux-gpio@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/5] gpio: mvebu: improve pwm period calculation accuracy
Date: Mon, 11 Jan 2021 13:17:03 +0200	[thread overview]
Message-ID: <b6fcb9829f06c1dfe2451ed57c84ba499b235022.1610362661.git.baruch@tkos.co.il> (raw)
In-Reply-To: <cover.1610362661.git.baruch@tkos.co.il>

Divide the full period value to reduce rounding error.

Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
---
 drivers/gpio/gpio-mvebu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
index a912a8fed197..c424d88e9e2b 100644
--- a/drivers/gpio/gpio-mvebu.c
+++ b/drivers/gpio/gpio-mvebu.c
@@ -715,9 +715,9 @@ static int mvebu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	else
 		on = 1;
 
-	val = (unsigned long long) mvpwm->clk_rate *
-		(state->period - state->duty_cycle);
+	val = (unsigned long long) mvpwm->clk_rate * state->period;
 	do_div(val, NSEC_PER_SEC);
+	val -= on;
 	if (val > UINT_MAX)
 		return -EINVAL;
 	if (val)
-- 
2.29.2


WARNING: multiple messages have this Message-ID (diff)
From: Baruch Siach <baruch@tkos.co.il>
To: "Thierry Reding" <thierry.reding@gmail.com>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"Lee Jones" <lee.jones@linaro.org>,
	"Linus Walleij" <linus.walleij@linaro.org>,
	"Bartosz Golaszewski" <bgolaszewski@baylibre.com>
Cc: Andrew Lunn <andrew@lunn.ch>, Baruch Siach <baruch@tkos.co.il>,
	linux-pwm@vger.kernel.org,
	Gregory Clement <gregory.clement@bootlin.com>,
	Russell King <linux@armlinux.org.uk>,
	linux-gpio@vger.kernel.org,
	Chris Packham <chris.packham@alliedtelesis.co.nz>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	Ralph Sennhauser <ralph.sennhauser@gmail.com>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	linux-arm-kernel@lists.infradead.org,
	Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Subject: [PATCH 2/5] gpio: mvebu: improve pwm period calculation accuracy
Date: Mon, 11 Jan 2021 13:17:03 +0200	[thread overview]
Message-ID: <b6fcb9829f06c1dfe2451ed57c84ba499b235022.1610362661.git.baruch@tkos.co.il> (raw)
In-Reply-To: <cover.1610362661.git.baruch@tkos.co.il>

Divide the full period value to reduce rounding error.

Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
---
 drivers/gpio/gpio-mvebu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
index a912a8fed197..c424d88e9e2b 100644
--- a/drivers/gpio/gpio-mvebu.c
+++ b/drivers/gpio/gpio-mvebu.c
@@ -715,9 +715,9 @@ static int mvebu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	else
 		on = 1;
 
-	val = (unsigned long long) mvpwm->clk_rate *
-		(state->period - state->duty_cycle);
+	val = (unsigned long long) mvpwm->clk_rate * state->period;
 	do_div(val, NSEC_PER_SEC);
+	val -= on;
 	if (val > UINT_MAX)
 		return -EINVAL;
 	if (val)
-- 
2.29.2


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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2021-01-11 11:18 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-11 11:17 [PATCH 0/5] gpio: mvebu: pwm fixes and improvements Baruch Siach
2021-01-11 11:17 ` Baruch Siach
2021-01-11 11:17 ` [PATCH 1/5] gpio: mvebu: fix pwm get_state period calculation Baruch Siach
2021-01-11 11:17   ` Baruch Siach
2021-01-11 20:17   ` Uwe Kleine-König
2021-01-11 20:17     ` Uwe Kleine-König
2021-01-13  6:36     ` Baruch Siach
2021-01-13  6:36       ` Baruch Siach
2021-01-13  8:17       ` Uwe Kleine-König
2021-01-13  8:17         ` Uwe Kleine-König
2021-01-11 11:17 ` Baruch Siach [this message]
2021-01-11 11:17   ` [PATCH 2/5] gpio: mvebu: improve pwm period calculation accuracy Baruch Siach
2021-01-11 20:18   ` Uwe Kleine-König
2021-01-11 20:18     ` Uwe Kleine-König
2021-01-11 11:17 ` [PATCH 3/5] gpio: mvebu: make pwm apply/get_state closer to idempotent Baruch Siach
2021-01-11 11:17   ` Baruch Siach
2021-01-11 20:20   ` Uwe Kleine-König
2021-01-11 20:20     ` Uwe Kleine-König
2021-01-11 11:17 ` [PATCH 4/5] gpio: mvebu: don't limit pwm period/duty_cycle to UINT_MAX Baruch Siach
2021-01-11 11:17   ` Baruch Siach
2021-01-11 20:21   ` Uwe Kleine-König
2021-01-11 20:21     ` Uwe Kleine-König
2021-01-11 11:17 ` [PATCH 5/5] gpio: mvebu: document zero pwm duty cycle limitation Baruch Siach
2021-01-11 11:17   ` Baruch Siach
2021-01-11 20:24   ` Uwe Kleine-König
2021-01-11 20:24     ` Uwe Kleine-König
2021-01-11 22:43     ` Russell King - ARM Linux admin
2021-01-11 22:43       ` Russell King - ARM Linux admin

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