* [PATCH v2 1/5] gpio: mvebu: fix pwm .get_state period calculation
2021-01-13 9:22 [PATCH v2 0/5] gpio: mvebu: pwm fixes and improvements Baruch Siach
@ 2021-01-13 9:22 ` Baruch Siach
2021-01-13 9:27 ` Uwe Kleine-König
2021-01-15 15:47 ` Thierry Reding
2021-01-13 9:22 ` [PATCH v2 2/5] gpio: mvebu: improve pwm period calculation accuracy Baruch Siach
` (4 subsequent siblings)
5 siblings, 2 replies; 11+ messages in thread
From: Baruch Siach @ 2021-01-13 9:22 UTC (permalink / raw)
To: Thierry Reding, Uwe Kleine-König, Lee Jones, Linus Walleij,
Bartosz Golaszewski
Cc: Baruch Siach, Russell King, Andrew Lunn, Gregory Clement,
Sebastian Hesselbarth, Thomas Petazzoni, Chris Packham,
Sascha Hauer, Ralph Sennhauser, linux-pwm, linux-gpio,
linux-arm-kernel
The period is the sum of on and off values. That is, calculate period as
($on + $off) / clkrate
instead of
$off / clkrate - $on / clkrate
that makes no sense.
Reported-by: Russell King <linux@armlinux.org.uk>
Fixes: 757642f9a584e ("gpio: mvebu: Add limited PWM support")
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
---
drivers/gpio/gpio-mvebu.c | 19 ++++++++-----------
1 file changed, 8 insertions(+), 11 deletions(-)
diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
index 672681a976f5..a912a8fed197 100644
--- a/drivers/gpio/gpio-mvebu.c
+++ b/drivers/gpio/gpio-mvebu.c
@@ -676,20 +676,17 @@ static void mvebu_pwm_get_state(struct pwm_chip *chip,
else
state->duty_cycle = 1;
+ val = (unsigned long long) u; /* on duration */
regmap_read(mvpwm->regs, mvebu_pwmreg_blink_off_duration(mvpwm), &u);
- val = (unsigned long long) u * NSEC_PER_SEC;
+ val += (unsigned long long) u; /* period = on + off duration */
+ val *= NSEC_PER_SEC;
do_div(val, mvpwm->clk_rate);
- if (val < state->duty_cycle) {
+ if (val > UINT_MAX)
+ state->period = UINT_MAX;
+ else if (val)
+ state->period = val;
+ else
state->period = 1;
- } else {
- val -= state->duty_cycle;
- if (val > UINT_MAX)
- state->period = UINT_MAX;
- else if (val)
- state->period = val;
- else
- state->period = 1;
- }
regmap_read(mvchip->regs, GPIO_BLINK_EN_OFF + mvchip->offset, &u);
if (u)
--
2.29.2
^ permalink raw reply related [flat|nested] 11+ messages in thread* Re: [PATCH v2 1/5] gpio: mvebu: fix pwm .get_state period calculation
2021-01-13 9:22 ` [PATCH v2 1/5] gpio: mvebu: fix pwm .get_state period calculation Baruch Siach
@ 2021-01-13 9:27 ` Uwe Kleine-König
2021-01-15 15:47 ` Thierry Reding
1 sibling, 0 replies; 11+ messages in thread
From: Uwe Kleine-König @ 2021-01-13 9:27 UTC (permalink / raw)
To: Baruch Siach
Cc: Thierry Reding, Lee Jones, Linus Walleij, Bartosz Golaszewski,
Russell King, Andrew Lunn, Gregory Clement,
Sebastian Hesselbarth, Thomas Petazzoni, Chris Packham,
Sascha Hauer, Ralph Sennhauser, linux-pwm, linux-gpio,
linux-arm-kernel
[-- Attachment #1: Type: text/plain, Size: 676 bytes --]
On Wed, Jan 13, 2021 at 11:22:41AM +0200, Baruch Siach wrote:
> The period is the sum of on and off values. That is, calculate period as
>
> ($on + $off) / clkrate
>
> instead of
>
> $off / clkrate - $on / clkrate
>
> that makes no sense.
>
> Reported-by: Russell King <linux@armlinux.org.uk>
> Fixes: 757642f9a584e ("gpio: mvebu: Add limited PWM support")
> Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
[-- Attachment #2: signature.asc --]
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^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [PATCH v2 1/5] gpio: mvebu: fix pwm .get_state period calculation
2021-01-13 9:22 ` [PATCH v2 1/5] gpio: mvebu: fix pwm .get_state period calculation Baruch Siach
2021-01-13 9:27 ` Uwe Kleine-König
@ 2021-01-15 15:47 ` Thierry Reding
1 sibling, 0 replies; 11+ messages in thread
From: Thierry Reding @ 2021-01-15 15:47 UTC (permalink / raw)
To: Baruch Siach
Cc: Uwe Kleine-König, Lee Jones, Linus Walleij,
Bartosz Golaszewski, Russell King, Andrew Lunn, Gregory Clement,
Sebastian Hesselbarth, Thomas Petazzoni, Chris Packham,
Sascha Hauer, Ralph Sennhauser, linux-pwm, linux-gpio,
linux-arm-kernel
On Wed, Jan 13, 2021 at 11:22:41AM +0200, Baruch Siach wrote:
> The period is the sum of on and off values. That is, calculate period as
>
> ($on + $off) / clkrate
>
> instead of
>
> $off / clkrate - $on / clkrate
>
> that makes no sense.
>
> Reported-by: Russell King <linux@armlinux.org.uk>
> Fixes: 757642f9a584e ("gpio: mvebu: Add limited PWM support")
> Signed-off-by: Baruch Siach <baruch@tkos.co.il>
> ---
> drivers/gpio/gpio-mvebu.c | 19 ++++++++-----------
> 1 file changed, 8 insertions(+), 11 deletions(-)
Acked-by: Thierry Reding <thierry.reding@gmail.com>
^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH v2 2/5] gpio: mvebu: improve pwm period calculation accuracy
2021-01-13 9:22 [PATCH v2 0/5] gpio: mvebu: pwm fixes and improvements Baruch Siach
2021-01-13 9:22 ` [PATCH v2 1/5] gpio: mvebu: fix pwm .get_state period calculation Baruch Siach
@ 2021-01-13 9:22 ` Baruch Siach
2021-01-13 9:22 ` [PATCH v2 3/5] gpio: mvebu: make pwm .get_state closer to idempotent Baruch Siach
` (3 subsequent siblings)
5 siblings, 0 replies; 11+ messages in thread
From: Baruch Siach @ 2021-01-13 9:22 UTC (permalink / raw)
To: Thierry Reding, Uwe Kleine-König, Lee Jones, Linus Walleij,
Bartosz Golaszewski
Cc: Baruch Siach, Andrew Lunn, Gregory Clement, Russell King,
Sebastian Hesselbarth, Thomas Petazzoni, Chris Packham,
Sascha Hauer, Ralph Sennhauser, linux-pwm, linux-gpio,
linux-arm-kernel
Change 'off' register value calculation from
$off = (period - duty_cycle) * clkrate / NSEC_PER_SEC
to
$off = (period * clkrate / NSEC_PER_SEC) - $on
That is, divide the full period value to reduce rounding error.
Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
---
drivers/gpio/gpio-mvebu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
index a912a8fed197..c424d88e9e2b 100644
--- a/drivers/gpio/gpio-mvebu.c
+++ b/drivers/gpio/gpio-mvebu.c
@@ -715,9 +715,9 @@ static int mvebu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
else
on = 1;
- val = (unsigned long long) mvpwm->clk_rate *
- (state->period - state->duty_cycle);
+ val = (unsigned long long) mvpwm->clk_rate * state->period;
do_div(val, NSEC_PER_SEC);
+ val -= on;
if (val > UINT_MAX)
return -EINVAL;
if (val)
--
2.29.2
^ permalink raw reply related [flat|nested] 11+ messages in thread* [PATCH v2 3/5] gpio: mvebu: make pwm .get_state closer to idempotent
2021-01-13 9:22 [PATCH v2 0/5] gpio: mvebu: pwm fixes and improvements Baruch Siach
2021-01-13 9:22 ` [PATCH v2 1/5] gpio: mvebu: fix pwm .get_state period calculation Baruch Siach
2021-01-13 9:22 ` [PATCH v2 2/5] gpio: mvebu: improve pwm period calculation accuracy Baruch Siach
@ 2021-01-13 9:22 ` Baruch Siach
2021-01-13 9:42 ` Uwe Kleine-König
2021-01-13 9:22 ` [PATCH v2 4/5] gpio: mvebu: don't limit pwm period/duty_cycle to UINT_MAX Baruch Siach
` (2 subsequent siblings)
5 siblings, 1 reply; 11+ messages in thread
From: Baruch Siach @ 2021-01-13 9:22 UTC (permalink / raw)
To: Thierry Reding, Uwe Kleine-König, Lee Jones, Linus Walleij,
Bartosz Golaszewski
Cc: Baruch Siach, Andrew Lunn, Gregory Clement, Russell King,
Sebastian Hesselbarth, Thomas Petazzoni, Chris Packham,
Sascha Hauer, Ralph Sennhauser, linux-pwm, linux-gpio,
linux-arm-kernel
Round up the result of division in period/duty_cycle calculation to make
the result closer to idempotent.
Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
---
drivers/gpio/gpio-mvebu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
index c424d88e9e2b..8673ba77af5a 100644
--- a/drivers/gpio/gpio-mvebu.c
+++ b/drivers/gpio/gpio-mvebu.c
@@ -668,7 +668,7 @@ static void mvebu_pwm_get_state(struct pwm_chip *chip,
regmap_read(mvpwm->regs, mvebu_pwmreg_blink_on_duration(mvpwm), &u);
val = (unsigned long long) u * NSEC_PER_SEC;
- do_div(val, mvpwm->clk_rate);
+ val = DIV_ROUND_UP_ULL(val, mvpwm->clk_rate);
if (val > UINT_MAX)
state->duty_cycle = UINT_MAX;
else if (val)
@@ -680,7 +680,7 @@ static void mvebu_pwm_get_state(struct pwm_chip *chip,
regmap_read(mvpwm->regs, mvebu_pwmreg_blink_off_duration(mvpwm), &u);
val += (unsigned long long) u; /* period = on + off duration */
val *= NSEC_PER_SEC;
- do_div(val, mvpwm->clk_rate);
+ val = DIV_ROUND_UP_ULL(val, mvpwm->clk_rate);
if (val > UINT_MAX)
state->period = UINT_MAX;
else if (val)
--
2.29.2
^ permalink raw reply related [flat|nested] 11+ messages in thread* Re: [PATCH v2 3/5] gpio: mvebu: make pwm .get_state closer to idempotent
2021-01-13 9:22 ` [PATCH v2 3/5] gpio: mvebu: make pwm .get_state closer to idempotent Baruch Siach
@ 2021-01-13 9:42 ` Uwe Kleine-König
0 siblings, 0 replies; 11+ messages in thread
From: Uwe Kleine-König @ 2021-01-13 9:42 UTC (permalink / raw)
To: Baruch Siach
Cc: Thierry Reding, Lee Jones, Linus Walleij, Bartosz Golaszewski,
Andrew Lunn, Gregory Clement, Russell King,
Sebastian Hesselbarth, Thomas Petazzoni, Chris Packham,
Sascha Hauer, Ralph Sennhauser, linux-pwm, linux-gpio,
linux-arm-kernel
[-- Attachment #1: Type: text/plain, Size: 705 bytes --]
On Wed, Jan 13, 2021 at 11:22:43AM +0200, Baruch Siach wrote:
> Round up the result of division in period/duty_cycle calculation to make
> the result closer to idempotent.
Maybe:
Round up the divisions in .get_state() to make applying the read out
configuration idempotent in most cases as .apply rounds down.
> Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Other than that:
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
[-- Attachment #2: signature.asc --]
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^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH v2 4/5] gpio: mvebu: don't limit pwm period/duty_cycle to UINT_MAX
2021-01-13 9:22 [PATCH v2 0/5] gpio: mvebu: pwm fixes and improvements Baruch Siach
` (2 preceding siblings ...)
2021-01-13 9:22 ` [PATCH v2 3/5] gpio: mvebu: make pwm .get_state closer to idempotent Baruch Siach
@ 2021-01-13 9:22 ` Baruch Siach
2021-01-13 9:22 ` [PATCH v2 5/5] gpio: mvebu: document zero pwm duty cycle limitation Baruch Siach
2021-01-18 13:45 ` [PATCH v2 0/5] gpio: mvebu: pwm fixes and improvements Linus Walleij
5 siblings, 0 replies; 11+ messages in thread
From: Baruch Siach @ 2021-01-13 9:22 UTC (permalink / raw)
To: Thierry Reding, Uwe Kleine-König, Lee Jones, Linus Walleij,
Bartosz Golaszewski
Cc: Baruch Siach, Andrew Lunn, Gregory Clement, Russell King,
Sebastian Hesselbarth, Thomas Petazzoni, Chris Packham,
Sascha Hauer, Ralph Sennhauser, linux-pwm, linux-gpio,
linux-arm-kernel
PWM on/off registers are limited to UINT_MAX. However the state period
and duty_cycle fields are ns values of type u64. There is no reason to
limit them to UINT_MAX.
Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
---
drivers/gpio/gpio-mvebu.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
index 8673ba77af5a..6b017854ce61 100644
--- a/drivers/gpio/gpio-mvebu.c
+++ b/drivers/gpio/gpio-mvebu.c
@@ -669,9 +669,7 @@ static void mvebu_pwm_get_state(struct pwm_chip *chip,
regmap_read(mvpwm->regs, mvebu_pwmreg_blink_on_duration(mvpwm), &u);
val = (unsigned long long) u * NSEC_PER_SEC;
val = DIV_ROUND_UP_ULL(val, mvpwm->clk_rate);
- if (val > UINT_MAX)
- state->duty_cycle = UINT_MAX;
- else if (val)
+ if (val)
state->duty_cycle = val;
else
state->duty_cycle = 1;
@@ -681,9 +679,7 @@ static void mvebu_pwm_get_state(struct pwm_chip *chip,
val += (unsigned long long) u; /* period = on + off duration */
val *= NSEC_PER_SEC;
val = DIV_ROUND_UP_ULL(val, mvpwm->clk_rate);
- if (val > UINT_MAX)
- state->period = UINT_MAX;
- else if (val)
+ if (val)
state->period = val;
else
state->period = 1;
--
2.29.2
^ permalink raw reply related [flat|nested] 11+ messages in thread* [PATCH v2 5/5] gpio: mvebu: document zero pwm duty cycle limitation
2021-01-13 9:22 [PATCH v2 0/5] gpio: mvebu: pwm fixes and improvements Baruch Siach
` (3 preceding siblings ...)
2021-01-13 9:22 ` [PATCH v2 4/5] gpio: mvebu: don't limit pwm period/duty_cycle to UINT_MAX Baruch Siach
@ 2021-01-13 9:22 ` Baruch Siach
2021-01-18 13:45 ` [PATCH v2 0/5] gpio: mvebu: pwm fixes and improvements Linus Walleij
5 siblings, 0 replies; 11+ messages in thread
From: Baruch Siach @ 2021-01-13 9:22 UTC (permalink / raw)
To: Thierry Reding, Uwe Kleine-König, Lee Jones, Linus Walleij,
Bartosz Golaszewski
Cc: Baruch Siach, Russell King, Andrew Lunn, Gregory Clement,
Sebastian Hesselbarth, Thomas Petazzoni, Chris Packham,
Sascha Hauer, Ralph Sennhauser, linux-pwm, linux-gpio,
linux-arm-kernel
Add a comment on why the code never sets on/off registers to zero.
Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Analyzed-by: Russell King <linux@armlinux.org.uk>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
---
drivers/gpio/gpio-mvebu.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
index 6b017854ce61..09780944bef9 100644
--- a/drivers/gpio/gpio-mvebu.c
+++ b/drivers/gpio/gpio-mvebu.c
@@ -706,6 +706,10 @@ static int mvebu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
do_div(val, NSEC_PER_SEC);
if (val > UINT_MAX)
return -EINVAL;
+ /*
+ * Zero on/off values don't work as expected. Experimentation shows
+ * that zero value is treated as 2^32. This behavior is not documented.
+ */
if (val)
on = val;
else
--
2.29.2
^ permalink raw reply related [flat|nested] 11+ messages in thread* Re: [PATCH v2 0/5] gpio: mvebu: pwm fixes and improvements
2021-01-13 9:22 [PATCH v2 0/5] gpio: mvebu: pwm fixes and improvements Baruch Siach
` (4 preceding siblings ...)
2021-01-13 9:22 ` [PATCH v2 5/5] gpio: mvebu: document zero pwm duty cycle limitation Baruch Siach
@ 2021-01-18 13:45 ` Linus Walleij
2021-01-18 14:59 ` Uwe Kleine-König
5 siblings, 1 reply; 11+ messages in thread
From: Linus Walleij @ 2021-01-18 13:45 UTC (permalink / raw)
To: Baruch Siach
Cc: Thierry Reding, Uwe Kleine-König, Lee Jones,
Bartosz Golaszewski, Andrew Lunn, Gregory Clement, Russell King,
Sebastian Hesselbarth, Thomas Petazzoni, Chris Packham,
Sascha Hauer, Ralph Sennhauser, linux-pwm,
open list:GPIO SUBSYSTEM, Linux ARM
On Wed, Jan 13, 2021 at 10:23 AM Baruch Siach <baruch@tkos.co.il> wrote:
> This series adds a few related fixes to the pwm .apply and .get_state
> callbacks.
>
> The first patch was originally part of the series adding Armada 8K/7K pwm
> support. I split it out to a separate series following review comments from
> Uwe Kleine-König who spotted a few more issues. There is no dependency between
> this and the Armada 8K/7K series.
This version looks really good and +/- minor tweaks as indicated by
Uwe:
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Yours,
Linus Walleij
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [PATCH v2 0/5] gpio: mvebu: pwm fixes and improvements
2021-01-18 13:45 ` [PATCH v2 0/5] gpio: mvebu: pwm fixes and improvements Linus Walleij
@ 2021-01-18 14:59 ` Uwe Kleine-König
0 siblings, 0 replies; 11+ messages in thread
From: Uwe Kleine-König @ 2021-01-18 14:59 UTC (permalink / raw)
To: Linus Walleij
Cc: Baruch Siach, Thierry Reding, Lee Jones, Bartosz Golaszewski,
Andrew Lunn, Gregory Clement, Russell King,
Sebastian Hesselbarth, Thomas Petazzoni, Chris Packham,
Sascha Hauer, Ralph Sennhauser, linux-pwm,
open list:GPIO SUBSYSTEM, Linux ARM
[-- Attachment #1: Type: text/plain, Size: 908 bytes --]
Hello Linus,
On Mon, Jan 18, 2021 at 02:45:14PM +0100, Linus Walleij wrote:
> On Wed, Jan 13, 2021 at 10:23 AM Baruch Siach <baruch@tkos.co.il> wrote:
>
> > This series adds a few related fixes to the pwm .apply and .get_state
> > callbacks.
> >
> > The first patch was originally part of the series adding Armada 8K/7K pwm
> > support. I split it out to a separate series following review comments from
> > Uwe Kleine-König who spotted a few more issues. There is no dependency between
> > this and the Armada 8K/7K series.
>
> This version looks really good and +/- minor tweaks as indicated by
> Uwe:
> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
The most recent version of this series is v4.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
^ permalink raw reply [flat|nested] 11+ messages in thread