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: 3
New patches: 0
Unchanged patches: 0
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 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 | 9 +++++----
3 files changed, 13 insertions(+), 20 deletions(-)
--
2.42.0
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 b07c8598bb21..7cf7a76cdb44 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);
}
--
2.42.0
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>;
};
};
--
2.42.0
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 | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c
index eabddb7c7820..b07c8598bb21 100644
--- a/drivers/pwm/pwm-sifive.c
+++ b/drivers/pwm/pwm-sifive.c
@@ -113,6 +113,7 @@ static int pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
u32 duty, val;
duty = readl(ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
+ duty = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - duty;
state->enabled = duty > 0;
@@ -123,11 +124,10 @@ 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;
}
-
static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
const struct pwm_state *state)
{
@@ -139,7 +139,7 @@ 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 +159,7 @@ 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) {
--
2.42.0
On Fri, Jan 26, 2024 at 03:40:43PM +0800, Nylon Chen wrote:
> 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]>
Reviewed-by: Conor Dooley <[email protected]>
Acked-by: Conor Dooley <[email protected]>
Uwe, take this with the driver, if that is ready to be taken.
Thanks,
Conor.
> ---
> 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>;
> };
> };
> --
> 2.42.0
>
Hello,
Regarding the Subject: The patch has nothing to do with an LED, has it?
On Fri, Jan 26, 2024 at 03:40:44PM +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.
Please break lines at 75 columns in the commit log.
> 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]
I looked at Figure 29 in this document (version v1p6, pdf page 148). Not
sure I understand that correctly, but I expect that the output of the
">=?" node below pwmcmp0 to become 1 if pwms has reached pwmcmp0, is
that right? In that case this output is zero when pwmcount is zero and
then pwmcmp0ip is zero, too. So a period starts with the inactive part
and so it's inversed polarity.
What made you think that the current driver implementation is wrong?
> 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 | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c
> index eabddb7c7820..b07c8598bb21 100644
> --- a/drivers/pwm/pwm-sifive.c
> +++ b/drivers/pwm/pwm-sifive.c
> @@ -113,6 +113,7 @@ static int pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> u32 duty, val;
>
> duty = readl(ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
> + duty = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - duty;
I find it irritating that both values are assigned to duty. I'd spend
another variable and make this:
inactive = readl(ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
duty = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - inactive;
>
> state->enabled = duty > 0;
>
> @@ -123,11 +124,10 @@ 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;
> }
> -
Please keep this empty line between functions.
> static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> const struct pwm_state *state)
> {
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2月6日 週二 上午2:07寫道：
>
> Hello,
Hi Uwe, thanks for your feedback.
>
> Regarding the Subject: The patch has nothing to do with an LED, has it?
I will correct this.
>
> On Fri, Jan 26, 2024 at 03:40:44PM +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.
>
> Please break lines at 75 columns in the commit log.
got it.
>
> > 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]
>
> I looked at Figure 29 in this document (version v1p6, pdf page 148). Not
> sure I understand that correctly, but I expect that the output of the
> ">=?" node below pwmcmp0 to become 1 if pwms has reached pwmcmp0, is
> that right? In that case this output is zero when pwmcount is zero and
> then pwmcmp0ip is zero, too. So a period starts with the inactive part
> and so it's inversed polarity.
>
> What made you think that the current driver implementation is wrong?
This is the process of my speculation.
This is a HiFive Unmatched/Unleashed LED-PWM layout
VDD
|
|
_____
\ / LED
\ /
---
|
|
|
______
| |
- |
^ --> |------ PWM
|___|___|
|
|
__
-
GND
- the waveform
e.g. duty=30s, period=100s, actvie-high = 30%, active-low = 70%
V
^
|
| ----------|
| |
| |
|______ |__________ > t
When VCC is high, the LED will be illuminated, which is an active-high
logic. This is why I want to remove "active-low".
For HW, we just focus on pwmcount/pwmcmp[0-3]
- pwmcount default is zero, that counter 0->1->0xffff
- Follow the origin algorithm the frac=0x0(on) / 0xffff(off) and when
the smaller the value of frac, the brighter the light.
-- E.g. pwmcmp = 0x2, pwmcount 0x0->0x1->...->0xffff
--- 0->0x2=low & 0x3->0xffff=high => 98%
-- E.g. pwmcmp = 0xffff, pwmcount 0x0->0x1->...->0xffff
--- 0->0xffff=low => 0%
- For SW, we reference the algorithm. (D=PW/T*100% D=duty_cycle,
T=period, PW=pulse width (pulse active time))
-- when we consider HW behavior
--- Direct writing SW frac into HW's pwmcmp is active low, so when
we want to get an active-high behavior that use a invert function.
If my understanding or deduction process is incorrect, please let me
know. Thank you.
>
> > 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 | 7 ++++---
> > 1 file changed, 4 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c
> > index eabddb7c7820..b07c8598bb21 100644
> > --- a/drivers/pwm/pwm-sifive.c
> > +++ b/drivers/pwm/pwm-sifive.c
> > @@ -113,6 +113,7 @@ static int pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> > u32 duty, val;
> >
> > duty = readl(ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
> > + duty = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - duty;
>
> I find it irritating that both values are assigned to duty. I'd spend
> another variable and make this:
>
> inactive = readl(ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
> duty = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - inactive;
got it.
>
>
> >
> > state->enabled = duty > 0;
> >
> > @@ -123,11 +124,10 @@ 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;
> > }
> > -
>
> Please keep this empty line between functions.
got it.
>
> > static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> > const struct pwm_state *state)
> > {
>
> Best regards
> Uwe
>
> --
> Pengutronix e.K. | Uwe Kleine-König |
> Industrial Linux Solutions | https://www.pengutronix.de/ |