pwm: lp3943: Fix duty calculation in case period was clamped

[ Upstream commit 5e3b07c ]

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: af66b3c ("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

@@ -125,6 +125,7 @@ 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);