diff mbox series

[v5,2/2] pwm: sifive: change the PWM controlled LED algorithm

Message ID 20231024101902.6689-3-nylon.chen@sifive.com
State New
Headers
Series Change PWM-controlled LED pin active mode and algorithm |

Commit Message

Nylon Chen Oct. 24, 2023, 10:19 a.m. UTC 
  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@sifive.com>
Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
---
 drivers/pwm/pwm-sifive.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

Comments

Nylon Chen Nov. 9, 2023, 7:02 a.m. UTC | #1 
Hi, Ping on the series.

Uwe, is there anything more I can do to push the process forward?

Nylon Chen <nylon.chen@sifive.com> 於 2023年10月24日 週二 下午6:19寫道：

>
> 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@sifive.com>
> Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
> ---
>  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);
>         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;
>         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);
>
>         mutex_lock(&ddata->lock);
> --
> 2.42.0
>
Krzysztof Kozlowski Nov. 9, 2023, 8:22 a.m. UTC | #2 
On 09/11/2023 08:02, Nylon Chen wrote:
> Hi, Ping on the series.
> 
> Uwe, is there anything more I can do to push the process forward?

It's merge window. What do you exactly expect to happen?

Best regards,
Krzysztof
Nylon Chen Dec. 6, 2023, 2:35 a.m. UTC | #3 
Hi Ping on the series.

The merge window should have ended.

Is there anything more I can do to push the process forward?

Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> 於 2023年11月9日 週四 下午4:22寫道：
>
> On 09/11/2023 08:02, Nylon Chen wrote:
> > Hi, Ping on the series.
> >
> > Uwe, is there anything more I can do to push the process forward?
>
> It's merge window. What do you exactly expect to happen?
>
> Best regards,
> Krzysztof
>
Uwe Kleine-König Dec. 11, 2023, 8:49 p.m. UTC | #4 
Hello Nylon,

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@sifive.com>
> Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
> ---
>  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.

>  	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?).

>  	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?

>  	mutex_lock(&ddata->lock);

Best regards
Uwe
Nylon Chen Jan. 8, 2024, 8:27 a.m. UTC | #5 
Uwe Kleine-König <u.kleine-koenig@pengutronix.de> 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@sifive.com>
> > Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
> > ---
> >  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/ |
Uwe Kleine-König Jan. 8, 2024, 9:25 a.m. UTC | #6 
Hello Nylon,

On Mon, Jan 08, 2024 at 04:27:40PM +0800, Nylon Chen wrote:
> Uwe Kleine-König <u.kleine-koenig@pengutronix.de> 於 2023年12月12日 週二 上午4:50寫道：
> > On Tue, Oct 24, 2023 at 06:19:02PM +0800, Nylon Chen wrote:
> > > 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.

That's very welcome, however I think this should be a separate change.

I'll think about the rest of your changes when you send a new patch.

Best regards
Uwe
diff mbox series

Patch

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);
 	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;
 	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);
 
 	mutex_lock(&ddata->lock);