[PATCH 4.14 146/218] pwm: lp3943: Fix duty calculation in case period was clamped

Greg Kroah-Hartman
2022-06-13T11:02:01Z

From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

[ Upstream commit 5e3b07ca5cc78cd4a987e78446849e41288d87cb ]

The hardware only supports periods <= 1.6 ms and if a bigger period is
requested it is clamped to 1.6 ms. In this case duty_cycle might be bigger
than 1.6 ms and then the duty cycle register is written with a value
bigger than LP3943_MAX_DUTY. So clamp duty_cycle accordingly.

Fixes: af66b3c0934e ("pwm: Add LP3943 PWM driver")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/pwm/pwm-lp3943.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/pwm/pwm-lp3943.c b/drivers/pwm/pwm-lp3943.c
index fc446d5c19f9..34151fc4cd51 100644
--- a/drivers/pwm/pwm-lp3943.c
+++ b/drivers/pwm/pwm-lp3943.c
@@ -128,6 +128,7 @@ static int lp3943_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
if (err)
return err;

+ duty_ns = min(duty_ns, period_ns);
val = (u8)(duty_ns * LP3943_MAX_DUTY / period_ns);

return lp3943_write_byte(lp3943, reg_duty, val);
--
2.35.1