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] Link: https://sifive.cdn.prismic.io/sifive/1a82e600-1f93-4f41-b2d8-86ed8b16acba_fu740-c000-manual-v1p6.pdf [0] Acked-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx> Reviewed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx> Signed-off-by: Nylon Chen <nylon.chen@xxxxxxxxxx> Signed-off-by: Vincent Chen <vincent.chen@xxxxxxxxxx> --- drivers/pwm/pwm-sifive.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c index 393a4b97fc19..d5d5f36da297 100644 --- a/drivers/pwm/pwm-sifive.c +++ b/drivers/pwm/pwm-sifive.c @@ -132,13 +132,13 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm, { struct pwm_sifive_ddata *ddata = pwm_sifive_chip_to_ddata(chip); struct pwm_state cur_state; - unsigned int duty_cycle; + unsigned int duty_cycle, period; unsigned long long num; bool enabled; int ret = 0; u32 frac; - if (state->polarity != PWM_POLARITY_INVERSED) + if (state->polarity != PWM_POLARITY_NORMAL && state->polarity != PWM_POLARITY_INVERSED) return -EINVAL; cur_state = pwm->state; @@ -154,10 +154,13 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm, * calculating the register values first and then writing them * consecutively */ + period = max(state->period, ddata->approx_period); num = (u64)duty_cycle * (1U << PWM_SIFIVE_CMPWIDTH); frac = DIV64_U64_ROUND_CLOSEST(num, state->period); - /* The hardware cannot generate a 100% duty cycle */ frac = min(frac, (1U << PWM_SIFIVE_CMPWIDTH) - 1); + /* The hardware cannot generate a 100% duty cycle */ + frac = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - frac; + mutex_lock(&ddata->lock); if (state->period != ddata->approx_period) { -- 2.40.0
