Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx> 於 2023年12月12日 週二 上午4:50寫道： > > Hello Nylon, Hi Uwe, thanks for your feedback. > > > > On Tue, Oct 24, 2023 at 06:19:02PM +0800, Nylon Chen wrote: > > 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] > > > > Signed-off-by: Nylon Chen <nylon.chen@xxxxxxxxxx> > > Signed-off-by: Vincent Chen <vincent.chen@xxxxxxxxxx> > > --- > > drivers/pwm/pwm-sifive.c | 10 ++++++---- > > 1 file changed, 6 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c > > index eabddb7c7820..353c2342fbf1 100644 > > --- a/drivers/pwm/pwm-sifive.c > > +++ b/drivers/pwm/pwm-sifive.c > > @@ -101,7 +101,7 @@ static void pwm_sifive_update_clock(struct pwm_sifive_ddata *ddata, > > > > /* As scale <= 15 the shift operation cannot overflow. */ > > num = (unsigned long long)NSEC_PER_SEC << (PWM_SIFIVE_CMPWIDTH + scale); > > - ddata->real_period = div64_ul(num, rate); > > + ddata->real_period = DIV_ROUND_UP_ULL(num, rate); > > It's unclear to me, why you changed that. Because there is a gap in idempotent tests. e.g. root@unmatched:~# echo 110 > /sys/devices/platform/led-controller-1/leds/d12/brightness [ 706.987712] .apply is not idempotent (ena=1 pol=0 1739692/4032985) -> (ena=1 pol=0 1739630/4032985) root@unmatched:~# echo 120 > /sys/devices/platform/led-controller-1/leds/d12/brightness [ 709.817554] .apply is not idempotent (ena=1 pol=0 1897846/4032985) -> (ena=1 pol=0 1897784/4032985) Round the result to the nearest whole number. This ensures that real_period is always a reasonable integer that is not lower than the actual value. After modification, idempotent errors can be avoided. > > > > dev_dbg(ddata->chip.dev, > > "New real_period = %u ns\n", ddata->real_period); > > } > > @@ -121,13 +121,14 @@ static int pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm, > > state->enabled = false; > > > > state->period = ddata->real_period; > > + > > + duty = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - duty; > > I would have placed that directly after > > duty = readl(...); > > which then also influences > > state->enabled = duty > 0; > > (as it should?). > Yes, you are right. I will make relevant corrections. ... duty = readl(ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm)); + duty = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - duty; - state->enabled = duty <= 65535; + state->enabled = duty > 0; ... state->period = ddata->real_period; - duty = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - duty; > > > state->duty_cycle = > > (u64)duty * ddata->real_period >> PWM_SIFIVE_CMPWIDTH; > > - state->polarity = PWM_POLARITY_INVERSED; > > + state->polarity = PWM_POLARITY_NORMAL; > > > > return 0; > > } > > - > > static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm, > > const struct pwm_state *state) > > { > > @@ -139,7 +140,7 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm, > > int ret = 0; > > u32 frac; > > > > - if (state->polarity != PWM_POLARITY_INVERSED) > > + if (state->polarity != PWM_POLARITY_NORMAL) > > return -EINVAL; > > > > cur_state = pwm->state; > > @@ -158,6 +159,7 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm, > > 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 = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - frac; > > frac = min(frac, (1U << PWM_SIFIVE_CMPWIDTH) - 1); > > frac can only be > (1U << PWM_SIFIVE_CMPWIDTH) - 1 if an overflow > happend the line above. Is that what you want here? I made a mistake, I pushed the wrong changes. I want to invert it after taking the minimum value, which makes sense to me. 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); > > Best regards > Uwe Best regards Nylon > > -- > Pengutronix e.K. | Uwe Kleine-König | > Industrial Linux Solutions | https://www.pengutronix.de/ |
