diff mbox series

[v9,3/3] pwm: sifive: Fix the error in the idempotent test within the pwm_apply_state_debug function

Message ID 20240222081231.213406-4-nylon.chen@sifive.com (mailing list archive)
State Handled Elsewhere
Headers show
Series Change PWM-controlled LED pin active mode and algorithm | expand

Checks

Context Check Description
conchuod/vmtest-for-next-PR success PR summary
conchuod/patch-3-test-1 success .github/scripts/patches/tests/build_rv32_defconfig.sh
conchuod/patch-3-test-2 success .github/scripts/patches/tests/build_rv64_clang_allmodconfig.sh
conchuod/patch-3-test-3 success .github/scripts/patches/tests/build_rv64_gcc_allmodconfig.sh
conchuod/patch-3-test-4 success .github/scripts/patches/tests/build_rv64_nommu_k210_defconfig.sh
conchuod/patch-3-test-5 success .github/scripts/patches/tests/build_rv64_nommu_virt_defconfig.sh
conchuod/patch-3-test-6 success .github/scripts/patches/tests/checkpatch.sh
conchuod/patch-3-test-7 success .github/scripts/patches/tests/dtb_warn_rv64.sh
conchuod/patch-3-test-8 success .github/scripts/patches/tests/header_inline.sh
conchuod/patch-3-test-9 success .github/scripts/patches/tests/kdoc.sh
conchuod/patch-3-test-10 success .github/scripts/patches/tests/module_param.sh
conchuod/patch-3-test-11 success .github/scripts/patches/tests/verify_fixes.sh
conchuod/patch-3-test-12 success .github/scripts/patches/tests/verify_signedoff.sh

Commit Message

Nylon Chen Feb. 22, 2024, 8:12 a.m. UTC 
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(-)

Comments

Uwe Kleine-König March 18, 2024, 6:17 p.m. UTC | #1 
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
Nylon Chen April 2, 2024, 2:01 a.m. UTC | #2 
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/ |
Uwe Kleine-König April 12, 2024, 7:05 a.m. UTC | #3 
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
Nylon Chen Dec. 24, 2024, 8:34 a.m. UTC | #4 
Uwe Kleine-König <u.kleine-koenig@pengutronix.de> 於 2024年4月12日 週五 下午3:05寫道：
>
> 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
>
Hi Uwe,
I apologize for the significant delay in responding to your query,
I've now completed a thorough verification of the PWM_DEBUG
functionality.

The Period Testing:
seq 5000 5000 100000 | while read p; do echo $p >
/sys/class/pwm/pwmchip0/pwm0/period echo "Testing period: $p" done

The Duty Cycle Testing:
for percent in 0 25 50 75 100; do duty=$((100000 * percent / 100))
echo $duty > /sys/class/pwm/pwmchip0/pwm0/duty_cycle done

- All period values from 5000ns to 100000ns were applied successfully
- Various duty cycle ratios were tested without issues
- Monitored dmesg output during tests - no kernel messages about wrong
settings were observed

Let me know if you need any additional test data or have other
parameters you'd like me to verify.

> and then verified that this test didn't result in kernel messages about
> wrong settings?
>
> Best regards
> Uwe
>
> --
> Pengutronix e.K.                           | Uwe Kleine-König            |
> Industrial Linux Solutions                 | https://www.pengutronix.de/ |
diff mbox series

Patch

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);
 }