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>,
Russell King <linux@armlinux.org.uk>,
Andrew Lunn <andrew@lunn.ch>,
Gregory Clement <gregory.clement@bootlin.com>,
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 v2 1/5] gpio: mvebu: fix pwm .get_state period calculation
Date: Wed, 13 Jan 2021 11:22:41 +0200 [thread overview]
Message-ID: <57860e4929a9d20d73f5e003a148b86a9f82310e.1610529002.git.baruch@tkos.co.il> (raw)
In-Reply-To: <cover.1610529002.git.baruch@tkos.co.il>
The period is the sum of on and off values. That is, calculate period as
($on + $off) / clkrate
instead of
$off / clkrate - $on / clkrate
that makes no sense.
Reported-by: Russell King <linux@armlinux.org.uk>
Fixes: 757642f9a584e ("gpio: mvebu: Add limited PWM support")
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
---
drivers/gpio/gpio-mvebu.c | 19 ++++++++-----------
1 file changed, 8 insertions(+), 11 deletions(-)
diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
index 672681a976f5..a912a8fed197 100644
--- a/drivers/gpio/gpio-mvebu.c
+++ b/drivers/gpio/gpio-mvebu.c
@@ -676,20 +676,17 @@ static void mvebu_pwm_get_state(struct pwm_chip *chip,
else
state->duty_cycle = 1;
+ val = (unsigned long long) u; /* on duration */
regmap_read(mvpwm->regs, mvebu_pwmreg_blink_off_duration(mvpwm), &u);
- val = (unsigned long long) u * NSEC_PER_SEC;
+ val += (unsigned long long) u; /* period = on + off duration */
+ val *= NSEC_PER_SEC;
do_div(val, mvpwm->clk_rate);
- if (val < state->duty_cycle) {
+ if (val > UINT_MAX)
+ state->period = UINT_MAX;
+ else if (val)
+ state->period = val;
+ else
state->period = 1;
- } else {
- val -= state->duty_cycle;
- if (val > UINT_MAX)
- state->period = UINT_MAX;
- else if (val)
- state->period = val;
- else
- state->period = 1;
- }
regmap_read(mvchip->regs, GPIO_BLINK_EN_OFF + mvchip->offset, &u);
if (u)
--
2.29.2
next prev parent reply other threads:[~2021-01-13 9:24 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-13 9:22 [PATCH v2 0/5] gpio: mvebu: pwm fixes and improvements Baruch Siach
2021-01-13 9:22 ` Baruch Siach [this message]
2021-01-13 9:27 ` [PATCH v2 1/5] gpio: mvebu: fix pwm .get_state period calculation Uwe Kleine-König
2021-01-15 15:47 ` Thierry Reding
2021-01-13 9:22 ` [PATCH v2 2/5] gpio: mvebu: improve pwm period calculation accuracy Baruch Siach
2021-01-13 9:22 ` [PATCH v2 3/5] gpio: mvebu: make pwm .get_state closer to idempotent Baruch Siach
2021-01-13 9:42 ` Uwe Kleine-König
2021-01-13 9:22 ` [PATCH v2 4/5] gpio: mvebu: don't limit pwm period/duty_cycle to UINT_MAX Baruch Siach
2021-01-13 9:22 ` [PATCH v2 5/5] gpio: mvebu: document zero pwm duty cycle limitation Baruch Siach
2021-01-18 13:45 ` [PATCH v2 0/5] gpio: mvebu: pwm fixes and improvements Linus Walleij
2021-01-18 14:59 ` Uwe Kleine-König
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