| Message ID | 20240222081231.213406-4-nylon.chen@sifive.com |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | Change PWM-controlled LED pin active mode and algorithm | expand |
Hello, On Thu, Feb 22, 2024 at 04:12:31PM +0800, Nylon Chen wrote: > 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. > > e.g. > $ echo 110 > /sys/devices/platform/led-controller-1/leds/d12/brightness > $ .apply is not idempotent (ena=1 pol=0 1739692/4032985) -> (ena=1 pol=0 1739630/4032985) > > Co-developed-by: Zong Li <zong.li@sifive.com> > Signed-off-by: Zong Li <zong.li@sifive.com> > Signed-off-by: Nylon Chen <nylon.chen@sifive.com> > --- > drivers/pwm/pwm-sifive.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c > index a586cfe4191b..bebcbebacccd 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); > dev_dbg(ddata->chip.dev, > "New real_period = %u ns\n", ddata->real_period); > } pwm_sifive_apply has a DIV64_U64_ROUND_CLOSEST(). I wonder if that needs adaption, too?! Best regards Uwe
Uwe Kleine-König <u.kleine-koenig@pengutronix.de> 於 2024年3月19日 週二 上午2:17寫道： > > Hello, > > On Thu, Feb 22, 2024 at 04:12:31PM +0800, Nylon Chen wrote: > > 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. > > > > e.g. > > $ echo 110 > /sys/devices/platform/led-controller-1/leds/d12/brightness > > $ .apply is not idempotent (ena=1 pol=0 1739692/4032985) -> (ena=1 pol=0 1739630/4032985) > > > > Co-developed-by: Zong Li <zong.li@sifive.com> > > Signed-off-by: Zong Li <zong.li@sifive.com> > > Signed-off-by: Nylon Chen <nylon.chen@sifive.com> > > --- > > drivers/pwm/pwm-sifive.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c > > index a586cfe4191b..bebcbebacccd 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); > > dev_dbg(ddata->chip.dev, > > "New real_period = %u ns\n", ddata->real_period); > > } Hi Uwe > > pwm_sifive_apply has a DIV64_U64_ROUND_CLOSEST(). I wonder if that needs > adaption, too?! According to my experiments, no adjustment is necessary. > > Best regards > Uwe > > -- > Pengutronix e.K. | Uwe Kleine-König | > Industrial Linux Solutions | https://www.pengutronix.de/ |
On Tue, Apr 02, 2024 at 10:01:39AM +0800, Nylon Chen wrote: > Uwe Kleine-König <u.kleine-koenig@pengutronix.de> 於 2024年3月19日 週二 上午2:17寫道： > > > > Hello, > > > > On Thu, Feb 22, 2024 at 04:12:31PM +0800, Nylon Chen wrote: > > > 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. > > > > > > e.g. > > > $ echo 110 > /sys/devices/platform/led-controller-1/leds/d12/brightness > > > $ .apply is not idempotent (ena=1 pol=0 1739692/4032985) -> (ena=1 pol=0 1739630/4032985) > > > > > > Co-developed-by: Zong Li <zong.li@sifive.com> > > > Signed-off-by: Zong Li <zong.li@sifive.com> > > > Signed-off-by: Nylon Chen <nylon.chen@sifive.com> > > > --- > > > drivers/pwm/pwm-sifive.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c > > > index a586cfe4191b..bebcbebacccd 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); > > > dev_dbg(ddata->chip.dev, > > > "New real_period = %u ns\n", ddata->real_period); > > > } > Hi Uwe > > > > pwm_sifive_apply has a DIV64_U64_ROUND_CLOSEST(). I wonder if that needs > > adaption, too?! > According to my experiments, no adjustment is necessary. Did you enable PWM_DEBUG and tested with something like: seq 5000 100000 | while read p; do echo p > /sys/class/pwm/pwmchipX/pwmY/period; done and then verified that this test didn't result in kernel messages about wrong settings? Best regards Uwe
diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c index a586cfe4191b..bebcbebacccd 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); dev_dbg(ddata->chip.dev, "New real_period = %u ns\n", ddata->real_period); }