[PATCH v2 2/2] pwm: sifive: change the PWM controlled LED algorithm

[Nylon Chen]

The `frac` variable represents the pulse inactive time, and the result of
this algorithm is the pulse active time. Therefore, we must reverse the
result.

The reference is SiFive FU740-C000 Manual[0].

[0]: https://sifive.cdn.prismic.io/sifive/1a82e600-1f93-4f41-b2d8-86ed8b16acba_fu740-c000-manual-v1p6.pdf

Signed-off-by: Nylon Chen <nylon.chen at sifive.com>
---
 drivers/pwm/pwm-sifive.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c
index 62b6acc6373d..a5eda165d071 100644
--- a/drivers/pwm/pwm-sifive.c
+++ b/drivers/pwm/pwm-sifive.c
@@ -158,6 +158,7 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	frac = DIV64_U64_ROUND_CLOSEST(num, state->period);
 	/* The hardware cannot generate a 100% duty cycle */
 	frac = min(frac, (1U << PWM_SIFIVE_CMPWIDTH) - 1);
+	frac = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - frac;
 
 	mutex_lock(&ddata->lock);
 	if (state->period != ddata->approx_period) {
-- 
2.36.1