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

From: Nylon Chen
Date: Fri Jan 13 2023 - 03:31:55 EST


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.

Signed-off-by: Nylon Chen <nylon.chen@xxxxxxxxxx>
Reviewed-by: Vincent Chen <vincent.chen@xxxxxxxxxx>
---
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