According to the circuit diagram of User LEDs - RGB described in the
manual hifive-unleashed-a00.pdf[0] and hifive-unmatched-schematics-v3.pdf[1].
The behavior of PWM is acitve-high.
According to the descriptionof PWM for pwmcmp in SiFive FU740-C000 Manual[2].
The pwm algorithm is (PW) pulse active time = (D) duty * (T) period.
The `frac` variable is pulse "inactive" time so we need to invert it.
So this patchset removes active-low in DTS and adds reverse logic to the driver.
Updated patches: 1
New patches: 0
Unchanged patches: 2
Links:
- [0]: https://sifive.cdn.prismic.io/sifive/c52a8e32-05ce-4aaf-95c8-7bf8453f8698_hifive-unleashed-a00-schematics-1.pdf
- [1]: https://sifive.cdn.prismic.io/sifive/6a06d6c0-6e66-49b5-8e9e-e68ce76f4192_hifive-unmatched-schematics-v3.pdf
- [2]: https://sifive.cdn.prismic.io/sifive/1a82e600-1f93-4f41-b2d8-86ed8b16acba_fu740-c000-manual-v1p6.pdf
Changed in v9:
- Fix commit message to adhere to 75 columns rule.
- Update commit message's subject.
- Add a variable for inactive logic.
Changed in v8:
- Fix Signed-off-by and Co-developed-by typo.
Changed in v7:
- Remove active-low strings from hifive-unleashed-a00.dts file.
Changed in v6:
- Separate the idempotent test bug fixes into a new patch.
- Move the reversing the duty before the line checking
state->enabled.
- Fix the algorithm and change it to take the minimum value first and
then reverse it.
Changed in v5:
- Add the updates to the PWM algorithm based on version 2 back in.
- Replace div64_ul with DIV_ROUND_UP_ULL to correct the error in the
period value of the idempotent test in pwm_apply_state_debug.
Changed in v4:
- Remove previous updates to the PWM algorithm.
Changed in v3:
- Convert the reference link to standard link.
- Move the inverted function before taking the minimum value.
- Change polarity check condition(high and low).
- Pick the biggest period length possible that is not bigger than the
requested period.
Changed in v2:
- Convert the reference link to standard link.
- Fix typo: s/sifive unmatched:/sifive: unmatched:/.
- Remove active-low from hifive-unleashed-a00.dts.
- Include this reference link in the dts and pwm commit messages.
Nylon Chen (3):
riscv: dts: sifive: unleashed/unmatched: Remove PWM controlled LED's
active-low properties
pwm: sifive: change the PWM controlled LED algorithm
pwm: sifive: Fix the error in the idempotent test within the
pwm_apply_state_debug function
arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts | 12 ++++--------
arch/riscv/boot/dts/sifive/hifive-unmatched-a00.dts | 12 ++++--------
drivers/pwm/pwm-sifive.c | 12 +++++++-----
3 files changed, 15 insertions(+), 21 deletions(-)
--
2.43.0
This removes the active-low properties of the PWM-controlled LEDs in
the HiFive Unmatched device tree.
The reference is hifive-unleashed-a00.pdf[0] and hifive-unmatched-schematics-v3.pdf[1].
Link: https://sifive.cdn.prismic.io/sifive/c52a8e32-05ce-4aaf-95c8-7bf8453f8698_hifive-unleashed-a00-schematics-1.pdf [0]
Link: https://sifive.cdn.prismic.io/sifive/6a06d6c0-6e66-49b5-8e9e-e68ce76f4192_hifive-unmatched-schematics-v3.pdf [1]
Co-developed-by: Zong Li <[email protected]>
Signed-off-by: Zong Li <[email protected]>
Co-developed-by: Vincent Chen <[email protected]>
Signed-off-by: Vincent Chen <[email protected]>
Signed-off-by: Nylon Chen <[email protected]>
---
arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts | 12 ++++--------
arch/riscv/boot/dts/sifive/hifive-unmatched-a00.dts | 12 ++++--------
2 files changed, 8 insertions(+), 16 deletions(-)
diff --git a/arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts b/arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts
index 900a50526d77..06731b8c7bc3 100644
--- a/arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts
+++ b/arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts
@@ -49,32 +49,28 @@ led-controller {
compatible = "pwm-leds";
led-d1 {
- pwms = <&pwm0 0 7812500 PWM_POLARITY_INVERTED>;
- active-low;
+ pwms = <&pwm0 0 7812500 0>;
color = <LED_COLOR_ID_GREEN>;
max-brightness = <255>;
label = "d1";
};
led-d2 {
- pwms = <&pwm0 1 7812500 PWM_POLARITY_INVERTED>;
- active-low;
+ pwms = <&pwm0 1 7812500 0>;
color = <LED_COLOR_ID_GREEN>;
max-brightness = <255>;
label = "d2";
};
led-d3 {
- pwms = <&pwm0 2 7812500 PWM_POLARITY_INVERTED>;
- active-low;
+ pwms = <&pwm0 2 7812500 0>;
color = <LED_COLOR_ID_GREEN>;
max-brightness = <255>;
label = "d3";
};
led-d4 {
- pwms = <&pwm0 3 7812500 PWM_POLARITY_INVERTED>;
- active-low;
+ pwms = <&pwm0 3 7812500 0>;
color = <LED_COLOR_ID_GREEN>;
max-brightness = <255>;
label = "d4";
diff --git a/arch/riscv/boot/dts/sifive/hifive-unmatched-a00.dts b/arch/riscv/boot/dts/sifive/hifive-unmatched-a00.dts
index 07387f9c135c..b328ee80693f 100644
--- a/arch/riscv/boot/dts/sifive/hifive-unmatched-a00.dts
+++ b/arch/riscv/boot/dts/sifive/hifive-unmatched-a00.dts
@@ -51,8 +51,7 @@ led-controller-1 {
compatible = "pwm-leds";
led-d12 {
- pwms = <&pwm0 0 7812500 PWM_POLARITY_INVERTED>;
- active-low;
+ pwms = <&pwm0 0 7812500 0>;
color = <LED_COLOR_ID_GREEN>;
max-brightness = <255>;
label = "d12";
@@ -68,20 +67,17 @@ multi-led {
label = "d2";
led-red {
- pwms = <&pwm0 2 7812500 PWM_POLARITY_INVERTED>;
- active-low;
+ pwms = <&pwm0 2 7812500 0>;
color = <LED_COLOR_ID_RED>;
};
led-green {
- pwms = <&pwm0 1 7812500 PWM_POLARITY_INVERTED>;
- active-low;
+ pwms = <&pwm0 1 7812500 0>;
color = <LED_COLOR_ID_GREEN>;
};
led-blue {
- pwms = <&pwm0 3 7812500 PWM_POLARITY_INVERTED>;
- active-low;
+ pwms = <&pwm0 3 7812500 0>;
color = <LED_COLOR_ID_BLUE>;
};
};
--
2.43.0
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]
Co-developed-by: Zong Li <[email protected]>
Signed-off-by: Zong Li <[email protected]>
Co-developed-by: Vincent Chen <[email protected]>
Signed-off-by: Vincent Chen <[email protected]>
Signed-off-by: Nylon Chen <[email protected]>
---
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..a586cfe4191b 100644
--- a/drivers/pwm/pwm-sifive.c
+++ b/drivers/pwm/pwm-sifive.c
@@ -110,9 +110,10 @@ static int pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
struct pwm_state *state)
{
struct pwm_sifive_ddata *ddata = pwm_sifive_chip_to_ddata(chip);
- u32 duty, val;
+ u32 duty, val, inactive;
- duty = readl(ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
+ inactive = readl(ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
+ duty = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - inactive;
state->enabled = duty > 0;
@@ -123,7 +124,7 @@ static int pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
state->period = ddata->real_period;
state->duty_cycle =
(u64)duty * ddata->real_period >> PWM_SIFIVE_CMPWIDTH;
- state->polarity = PWM_POLARITY_INVERSED;
+ state->polarity = PWM_POLARITY_NORMAL;
return 0;
}
@@ -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;
@@ -159,6 +160,7 @@ 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) {
--
2.43.0
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 <[email protected]>
Signed-off-by: Zong Li <[email protected]>
Signed-off-by: Nylon Chen <[email protected]>
---
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);
}
--
2.43.0
On Thu, Feb 22, 2024 at 04:12:30PM +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]
>
> Co-developed-by: Zong Li <[email protected]>
> Signed-off-by: Zong Li <[email protected]>
> Co-developed-by: Vincent Chen <[email protected]>
> Signed-off-by: Vincent Chen <[email protected]>
> Signed-off-by: Nylon Chen <[email protected]>
> ---
> 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..a586cfe4191b 100644
> --- a/drivers/pwm/pwm-sifive.c
> +++ b/drivers/pwm/pwm-sifive.c
> @@ -110,9 +110,10 @@ static int pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> struct pwm_state *state)
> {
> struct pwm_sifive_ddata *ddata = pwm_sifive_chip_to_ddata(chip);
> - u32 duty, val;
> + u32 duty, val, inactive;
>
> - duty = readl(ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
> + inactive = readl(ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
> + duty = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - inactive;
>
> state->enabled = duty > 0;
>
> @@ -123,7 +124,7 @@ static int pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> state->period = ddata->real_period;
> state->duty_cycle =
> (u64)duty * ddata->real_period >> PWM_SIFIVE_CMPWIDTH;
> - state->polarity = PWM_POLARITY_INVERSED;
> + state->polarity = PWM_POLARITY_NORMAL;
>
> return 0;
> }
> @@ -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;
> @@ -159,6 +160,7 @@ 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 */
Is this still true now that we know that PWM_SIFIVE_PWMCMP is the
inactive time in a period? If you fix that, the same claim in the header
of the driver needs adaption, too.
> frac = min(frac, (1U << PWM_SIFIVE_CMPWIDTH) - 1);
> + frac = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - frac;
I like the additional variable in pwm_sifive_get_state(). Can you please
add one here, too?
> mutex_lock(&ddata->lock);
> if (state->period != ddata->approx_period) {
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-K?nig |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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 <[email protected]>
> Signed-off-by: Zong Li <[email protected]>
> Signed-off-by: Nylon Chen <[email protected]>
> ---
> 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
--
Pengutronix e.K. | Uwe Kleine-K?nig |
Industrial Linux Solutions | https://www.pengutronix.de/ |
Uwe Kleine-König <[email protected]> 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 <[email protected]>
> > Signed-off-by: Zong Li <[email protected]>
> > Signed-off-by: Nylon Chen <[email protected]>
> > ---
> > 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 <[email protected]> 於 2024年3月19日 週二 上午2:16寫道：
>
> On Thu, Feb 22, 2024 at 04:12:30PM +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]
> >
> > Co-developed-by: Zong Li <[email protected]>
> > Signed-off-by: Zong Li <[email protected]>
> > Co-developed-by: Vincent Chen <[email protected]>
> > Signed-off-by: Vincent Chen <[email protected]>
> > Signed-off-by: Nylon Chen <[email protected]>
> > ---
> > 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..a586cfe4191b 100644
> > --- a/drivers/pwm/pwm-sifive.c
> > +++ b/drivers/pwm/pwm-sifive.c
> > @@ -110,9 +110,10 @@ static int pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> > struct pwm_state *state)
> > {
> > struct pwm_sifive_ddata *ddata = pwm_sifive_chip_to_ddata(chip);
> > - u32 duty, val;
> > + u32 duty, val, inactive;
> >
> > - duty = readl(ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
> > + inactive = readl(ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
> > + duty = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - inactive;
> >
> > state->enabled = duty > 0;
> >
> > @@ -123,7 +124,7 @@ static int pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> > state->period = ddata->real_period;
> > state->duty_cycle =
> > (u64)duty * ddata->real_period >> PWM_SIFIVE_CMPWIDTH;
> > - state->polarity = PWM_POLARITY_INVERSED;
> > + state->polarity = PWM_POLARITY_NORMAL;
> >
> > return 0;
> > }
> > @@ -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;
> > @@ -159,6 +160,7 @@ 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 */
>
> Is this still true now that we know that PWM_SIFIVE_PWMCMP is the
> inactive time in a period? If you fix that, the same claim in the header
> of the driver needs adaption, too.
I believe the statement is true, but I don't know which part the
driver header file refers to.
>
> > frac = min(frac, (1U << PWM_SIFIVE_CMPWIDTH) - 1);
> > + frac = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - frac;
>
> I like the additional variable in pwm_sifive_get_state(). Can you please
> add one here, too?
got it
>
> > mutex_lock(&ddata->lock);
> > if (state->period != ddata->approx_period) {
>
Thank you for taking the time to help me review my implementation.
Nylon
> Best regards
> Uwe
>
> --
> Pengutronix e.K. | Uwe Kleine-König |
> Industrial Linux Solutions | https://www.pengutronix.de/ |
Nylon Chen <[email protected]> 於 2024年4月2日 週二 上午10:08寫道：
>
> Uwe Kleine-König <[email protected]> 於 2024年3月19日 週二 上午2:16寫道：
> >
> > On Thu, Feb 22, 2024 at 04:12:30PM +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]
> > >
> > > Co-developed-by: Zong Li <[email protected]>
> > > Signed-off-by: Zong Li <[email protected]>
> > > Co-developed-by: Vincent Chen <[email protected]>
> > > Signed-off-by: Vincent Chen <[email protected]>
> > > Signed-off-by: Nylon Chen <[email protected]>
> > > ---
> > > 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..a586cfe4191b 100644
> > > --- a/drivers/pwm/pwm-sifive.c
> > > +++ b/drivers/pwm/pwm-sifive.c
> > > @@ -110,9 +110,10 @@ static int pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> > > struct pwm_state *state)
> > > {
> > > struct pwm_sifive_ddata *ddata = pwm_sifive_chip_to_ddata(chip);
> > > - u32 duty, val;
> > > + u32 duty, val, inactive;
> > >
> > > - duty = readl(ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
> > > + inactive = readl(ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
> > > + duty = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - inactive;
> > >
> > > state->enabled = duty > 0;
> > >
> > > @@ -123,7 +124,7 @@ static int pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> > > state->period = ddata->real_period;
> > > state->duty_cycle =
> > > (u64)duty * ddata->real_period >> PWM_SIFIVE_CMPWIDTH;
> > > - state->polarity = PWM_POLARITY_INVERSED;
> > > + state->polarity = PWM_POLARITY_NORMAL;
> > >
> > > return 0;
> > > }
> > > @@ -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;
> > > @@ -159,6 +160,7 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> > > frac = DIV64_U64_ROUND_CLOSEST(num, state->period);
Hi Uwe,
> > > /* The hardware cannot generate a 100% duty cycle */
Do you mean that if the inference is correct, this comment should be modified?
> >
> > Is this still true now that we know that PWM_SIFIVE_PWMCMP is the
> > inactive time in a period? If you fix that, the same claim in the header
> > of the driver needs adaption, too.
> I believe the statement is true, but I don't know which part the
> driver header file refers to.
> >
> > > frac = min(frac, (1U << PWM_SIFIVE_CMPWIDTH) - 1);
> > > + frac = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - frac;
> >
> > I like the additional variable in pwm_sifive_get_state(). Can you please
> > add one here, too?
> got it
> >
> > > mutex_lock(&ddata->lock);
> > > if (state->period != ddata->approx_period) {
> >
> Thank you for taking the time to help me review my implementation.
>
> Nylon
> > Best regards
> > Uwe
> >
> > --
> > Pengutronix e.K. | Uwe Kleine-König |
> > Industrial Linux Solutions | https://www.pengutronix.de/ |
Hello,
On Fri, Apr 12, 2024 at 10:07:12AM +0800, Nylon Chen wrote:
> Nylon Chen <[email protected]> 於 2024年4月2日 週二 上午10:08寫道：
> > Uwe Kleine-König <[email protected]> 於 2024年3月19日 週二 上午2:16寫道：
> > > On Thu, Feb 22, 2024 at 04:12:30PM +0800, Nylon Chen wrote:
> > > > /* The hardware cannot generate a 100% duty cycle */
> Do you mean that if the inference is correct, this comment should be modified?
If the polarity was wrong before and the hardware was believed to not be
able to generate a 100% relative duty cycle, then maybe it's really a 0%
relative duty cycle that's impossible?
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 <[email protected]> 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 <[email protected]>
> > > Signed-off-by: Zong Li <[email protected]>
> > > Signed-off-by: Nylon Chen <[email protected]>
> > > ---
> > > 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
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |