Thread (14 messages) 14 messages, 3 authors, 2021-01-13
STALE1991d
Revisions (5)
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[PATCH 2/5] gpio: mvebu: improve pwm period calculation accuracy

From: Baruch Siach <baruch@tkos.co.il>
Date: 2021-01-11 11:18:26
Also in: linux-arm-kernel, linux-pwm
Subsystem: gpio subsystem, the rest · Maintainers: Linus Walleij, Bartosz Golaszewski, Linus Torvalds

Divide the full period value to reduce rounding error.

Reported-by: Uwe Kleine-König <redacted>
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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