* [PATCH v5 0/4] gpio: mvebu: pwm fixes and improvements
@ 2021-01-20 16:16 ` Baruch Siach
0 siblings, 0 replies; 14+ messages in thread
From: Baruch Siach @ 2021-01-20 16:16 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
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.
v5:
* Drop a patch applied to the gpio tree
* Fix patch 4/4 description typo (Uwe)
* Reduce the number of multiplications (Uwe)
* Add spaces around '+' (Uwe)
* Use '1ULL' instead of explicit cast to reduce verbosity
* Add Linus' Reviewed-by tags to patches that are unchanged since v2
v4:
* Take advantage of zero value being treated as 2^32 by hardware. Rewrite
patch 5/5 (Uwe).
v3:
* Improve patch 3/5 description (Uwe)
* Add more Reviewed-by tags from Uwe
v2:
Address Uwe Kleine-König comments.
* Improve patch 1/5 summary line
* Add more information to patch 1/5 description
* Add more information to patch 2/5 description
* Don't round period/duty_cycle up in .apply (patch 3/5)
* Expand the comment in path 5/5 based on RMK's analysis of hardware
behaviour
* Add Uwe's Reviewed-by tags
Baruch Siach (4):
gpio: mvebu: improve pwm period calculation accuracy
gpio: mvebu: make pwm .get_state closer to idempotent
gpio: mvebu: don't limit pwm period/duty_cycle to UINT_MAX
gpio: mvebu: improve handling of pwm zero on/off values
drivers/gpio/gpio-mvebu.c | 47 +++++++++++++++++++++------------------
1 file changed, 25 insertions(+), 22 deletions(-)
--
2.29.2
^ permalink raw reply [flat|nested] 14+ messages in thread
* [PATCH v5 0/4] gpio: mvebu: pwm fixes and improvements
@ 2021-01-20 16:16 ` Baruch Siach
0 siblings, 0 replies; 14+ messages in thread
From: Baruch Siach @ 2021-01-20 16:16 UTC (permalink / raw)
To: Thierry Reding, Uwe Kleine-König, Lee Jones, Linus Walleij,
Bartosz Golaszewski
Cc: Andrew Lunn, Baruch Siach, linux-pwm, Gregory Clement,
Russell King, linux-gpio, Chris Packham, Thomas Petazzoni,
Ralph Sennhauser, Sascha Hauer, linux-arm-kernel,
Sebastian Hesselbarth
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.
v5:
* Drop a patch applied to the gpio tree
* Fix patch 4/4 description typo (Uwe)
* Reduce the number of multiplications (Uwe)
* Add spaces around '+' (Uwe)
* Use '1ULL' instead of explicit cast to reduce verbosity
* Add Linus' Reviewed-by tags to patches that are unchanged since v2
v4:
* Take advantage of zero value being treated as 2^32 by hardware. Rewrite
patch 5/5 (Uwe).
v3:
* Improve patch 3/5 description (Uwe)
* Add more Reviewed-by tags from Uwe
v2:
Address Uwe Kleine-König comments.
* Improve patch 1/5 summary line
* Add more information to patch 1/5 description
* Add more information to patch 2/5 description
* Don't round period/duty_cycle up in .apply (patch 3/5)
* Expand the comment in path 5/5 based on RMK's analysis of hardware
behaviour
* Add Uwe's Reviewed-by tags
Baruch Siach (4):
gpio: mvebu: improve pwm period calculation accuracy
gpio: mvebu: make pwm .get_state closer to idempotent
gpio: mvebu: don't limit pwm period/duty_cycle to UINT_MAX
gpio: mvebu: improve handling of pwm zero on/off values
drivers/gpio/gpio-mvebu.c | 47 +++++++++++++++++++++------------------
1 file changed, 25 insertions(+), 22 deletions(-)
--
2.29.2
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 14+ messages in thread
* [PATCH v5 1/4] gpio: mvebu: improve pwm period calculation accuracy
2021-01-20 16:16 ` Baruch Siach
@ 2021-01-20 16:16 ` Baruch Siach
-1 siblings, 0 replies; 14+ messages in thread
From: Baruch Siach @ 2021-01-20 16:16 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>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
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] 14+ messages in thread
* [PATCH v5 1/4] gpio: mvebu: improve pwm period calculation accuracy
@ 2021-01-20 16:16 ` Baruch Siach
0 siblings, 0 replies; 14+ messages in thread
From: Baruch Siach @ 2021-01-20 16:16 UTC (permalink / raw)
To: Thierry Reding, Uwe Kleine-König, Lee Jones, Linus Walleij,
Bartosz Golaszewski
Cc: Andrew Lunn, Baruch Siach, linux-pwm, Gregory Clement,
Russell King, linux-gpio, Chris Packham, Thomas Petazzoni,
Ralph Sennhauser, Sascha Hauer, linux-arm-kernel,
Sebastian Hesselbarth
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>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
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
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 14+ messages in thread
* [PATCH v5 2/4] gpio: mvebu: make pwm .get_state closer to idempotent
2021-01-20 16:16 ` Baruch Siach
@ 2021-01-20 16:16 ` Baruch Siach
-1 siblings, 0 replies; 14+ messages in thread
From: Baruch Siach @ 2021-01-20 16:16 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 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>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
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] 14+ messages in thread
* [PATCH v5 2/4] gpio: mvebu: make pwm .get_state closer to idempotent
@ 2021-01-20 16:16 ` Baruch Siach
0 siblings, 0 replies; 14+ messages in thread
From: Baruch Siach @ 2021-01-20 16:16 UTC (permalink / raw)
To: Thierry Reding, Uwe Kleine-König, Lee Jones, Linus Walleij,
Bartosz Golaszewski
Cc: Andrew Lunn, Baruch Siach, linux-pwm, Gregory Clement,
Russell King, linux-gpio, Chris Packham, Thomas Petazzoni,
Ralph Sennhauser, Sascha Hauer, linux-arm-kernel,
Sebastian Hesselbarth
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>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
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
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 14+ messages in thread
* [PATCH v5 3/4] gpio: mvebu: don't limit pwm period/duty_cycle to UINT_MAX
2021-01-20 16:16 ` Baruch Siach
@ 2021-01-20 16:16 ` Baruch Siach
-1 siblings, 0 replies; 14+ messages in thread
From: Baruch Siach @ 2021-01-20 16:16 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>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
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] 14+ messages in thread
* [PATCH v5 3/4] gpio: mvebu: don't limit pwm period/duty_cycle to UINT_MAX
@ 2021-01-20 16:16 ` Baruch Siach
0 siblings, 0 replies; 14+ messages in thread
From: Baruch Siach @ 2021-01-20 16:16 UTC (permalink / raw)
To: Thierry Reding, Uwe Kleine-König, Lee Jones, Linus Walleij,
Bartosz Golaszewski
Cc: Andrew Lunn, Baruch Siach, linux-pwm, Gregory Clement,
Russell King, linux-gpio, Chris Packham, Thomas Petazzoni,
Ralph Sennhauser, Sascha Hauer, linux-arm-kernel,
Sebastian Hesselbarth
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>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
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
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 14+ messages in thread
* [PATCH v5 4/4] gpio: mvebu: improve handling of pwm zero on/off values
2021-01-20 16:16 ` Baruch Siach
@ 2021-01-20 16:16 ` Baruch Siach
-1 siblings, 0 replies; 14+ messages in thread
From: Baruch Siach @ 2021-01-20 16:16 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
Hardware appears to treat zero value as 2^32. Take advantage of this
fact to support on/off values of up to UINT_MAX+1 == 2^32. Adjust both
.apply and .get_state to handle zero as a special case.
Rounded up division result in .get_state can't be zero, since the
dividend is now larger than 0. Remove check for this case.
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 | 39 +++++++++++++++++++++++----------------
1 file changed, 23 insertions(+), 16 deletions(-)
diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
index 6b017854ce61..75e3c235bd3a 100644
--- a/drivers/gpio/gpio-mvebu.c
+++ b/drivers/gpio/gpio-mvebu.c
@@ -667,22 +667,21 @@ static void mvebu_pwm_get_state(struct pwm_chip *chip,
spin_lock_irqsave(&mvpwm->lock, flags);
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)
- state->duty_cycle = val;
+ /* Hardware treats zero as 2^32. See mvebu_pwm_apply(). */
+ if (u > 0)
+ val = u;
else
- state->duty_cycle = 1;
+ val = UINT_MAX + 1ULL;
+ state->duty_cycle = DIV_ROUND_UP_ULL(val * NSEC_PER_SEC,
+ mvpwm->clk_rate);
- val = (unsigned long long) u; /* on duration */
regmap_read(mvpwm->regs, mvebu_pwmreg_blink_off_duration(mvpwm), &u);
- val += (unsigned long long) u; /* period = on + off duration */
- val *= NSEC_PER_SEC;
- val = DIV_ROUND_UP_ULL(val, mvpwm->clk_rate);
- if (val)
- state->period = val;
+ /* period = on + off duration */
+ if (u > 0)
+ val += u;
else
- state->period = 1;
+ val += UINT_MAX + 1ULL;
+ state->period = DIV_ROUND_UP_ULL(val * NSEC_PER_SEC, mvpwm->clk_rate);
regmap_read(mvchip->regs, GPIO_BLINK_EN_OFF + mvchip->offset, &u);
if (u)
@@ -704,9 +703,15 @@ static int mvebu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
val = (unsigned long long) mvpwm->clk_rate * state->duty_cycle;
do_div(val, NSEC_PER_SEC);
- if (val > UINT_MAX)
+ if (val > UINT_MAX + 1ULL)
return -EINVAL;
- if (val)
+ /*
+ * 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 == UINT_MAX + 1ULL)
+ on = 0;
+ else if (val)
on = val;
else
on = 1;
@@ -714,9 +719,11 @@ static int mvebu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
val = (unsigned long long) mvpwm->clk_rate * state->period;
do_div(val, NSEC_PER_SEC);
val -= on;
- if (val > UINT_MAX)
+ if (val > UINT_MAX + 1ULL)
return -EINVAL;
- if (val)
+ if (val == UINT_MAX + 1ULL)
+ off = 0;
+ else if (val)
off = val;
else
off = 1;
--
2.29.2
^ permalink raw reply related [flat|nested] 14+ messages in thread
* [PATCH v5 4/4] gpio: mvebu: improve handling of pwm zero on/off values
@ 2021-01-20 16:16 ` Baruch Siach
0 siblings, 0 replies; 14+ messages in thread
From: Baruch Siach @ 2021-01-20 16:16 UTC (permalink / raw)
To: Thierry Reding, Uwe Kleine-König, Lee Jones, Linus Walleij,
Bartosz Golaszewski
Cc: Andrew Lunn, Baruch Siach, linux-pwm, Gregory Clement,
Russell King, linux-gpio, Chris Packham, Thomas Petazzoni,
Ralph Sennhauser, Sascha Hauer, linux-arm-kernel,
Sebastian Hesselbarth
Hardware appears to treat zero value as 2^32. Take advantage of this
fact to support on/off values of up to UINT_MAX+1 == 2^32. Adjust both
.apply and .get_state to handle zero as a special case.
Rounded up division result in .get_state can't be zero, since the
dividend is now larger than 0. Remove check for this case.
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 | 39 +++++++++++++++++++++++----------------
1 file changed, 23 insertions(+), 16 deletions(-)
diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
index 6b017854ce61..75e3c235bd3a 100644
--- a/drivers/gpio/gpio-mvebu.c
+++ b/drivers/gpio/gpio-mvebu.c
@@ -667,22 +667,21 @@ static void mvebu_pwm_get_state(struct pwm_chip *chip,
spin_lock_irqsave(&mvpwm->lock, flags);
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)
- state->duty_cycle = val;
+ /* Hardware treats zero as 2^32. See mvebu_pwm_apply(). */
+ if (u > 0)
+ val = u;
else
- state->duty_cycle = 1;
+ val = UINT_MAX + 1ULL;
+ state->duty_cycle = DIV_ROUND_UP_ULL(val * NSEC_PER_SEC,
+ mvpwm->clk_rate);
- val = (unsigned long long) u; /* on duration */
regmap_read(mvpwm->regs, mvebu_pwmreg_blink_off_duration(mvpwm), &u);
- val += (unsigned long long) u; /* period = on + off duration */
- val *= NSEC_PER_SEC;
- val = DIV_ROUND_UP_ULL(val, mvpwm->clk_rate);
- if (val)
- state->period = val;
+ /* period = on + off duration */
+ if (u > 0)
+ val += u;
else
- state->period = 1;
+ val += UINT_MAX + 1ULL;
+ state->period = DIV_ROUND_UP_ULL(val * NSEC_PER_SEC, mvpwm->clk_rate);
regmap_read(mvchip->regs, GPIO_BLINK_EN_OFF + mvchip->offset, &u);
if (u)
@@ -704,9 +703,15 @@ static int mvebu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
val = (unsigned long long) mvpwm->clk_rate * state->duty_cycle;
do_div(val, NSEC_PER_SEC);
- if (val > UINT_MAX)
+ if (val > UINT_MAX + 1ULL)
return -EINVAL;
- if (val)
+ /*
+ * 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 == UINT_MAX + 1ULL)
+ on = 0;
+ else if (val)
on = val;
else
on = 1;
@@ -714,9 +719,11 @@ static int mvebu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
val = (unsigned long long) mvpwm->clk_rate * state->period;
do_div(val, NSEC_PER_SEC);
val -= on;
- if (val > UINT_MAX)
+ if (val > UINT_MAX + 1ULL)
return -EINVAL;
- if (val)
+ if (val == UINT_MAX + 1ULL)
+ off = 0;
+ else if (val)
off = val;
else
off = 1;
--
2.29.2
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^ permalink raw reply related [flat|nested] 14+ messages in thread
* Re: [PATCH v5 4/4] gpio: mvebu: improve handling of pwm zero on/off values
2021-01-20 16:16 ` Baruch Siach
@ 2021-01-20 17:24 ` Uwe Kleine-König
-1 siblings, 0 replies; 14+ messages in thread
From: Uwe Kleine-König @ 2021-01-20 17:24 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: 817 bytes --]
On Wed, Jan 20, 2021 at 06:16:28PM +0200, Baruch Siach wrote:
> Hardware appears to treat zero value as 2^32. Take advantage of this
> fact to support on/off values of up to UINT_MAX+1 == 2^32. Adjust both
> .apply and .get_state to handle zero as a special case.
>
> Rounded up division result in .get_state can't be zero, since the
> dividend is now larger than 0. Remove check for this case.
>
> 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>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Thanks
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] 14+ messages in thread
* Re: [PATCH v5 4/4] gpio: mvebu: improve handling of pwm zero on/off values
@ 2021-01-20 17:24 ` Uwe Kleine-König
0 siblings, 0 replies; 14+ messages in thread
From: Uwe Kleine-König @ 2021-01-20 17:24 UTC (permalink / raw)
To: Baruch Siach
Cc: Andrew Lunn, Sascha Hauer, linux-pwm, Linus Walleij,
Chris Packham, Russell King, Bartosz Golaszewski, Thierry Reding,
Thomas Petazzoni, linux-gpio, Ralph Sennhauser, Lee Jones,
Gregory Clement, linux-arm-kernel, Sebastian Hesselbarth
[-- Attachment #1.1: Type: text/plain, Size: 817 bytes --]
On Wed, Jan 20, 2021 at 06:16:28PM +0200, Baruch Siach wrote:
> Hardware appears to treat zero value as 2^32. Take advantage of this
> fact to support on/off values of up to UINT_MAX+1 == 2^32. Adjust both
> .apply and .get_state to handle zero as a special case.
>
> Rounded up division result in .get_state can't be zero, since the
> dividend is now larger than 0. Remove check for this case.
>
> 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>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Thanks
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
[-- Attachment #1.2: signature.asc --]
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[-- Attachment #2: Type: text/plain, Size: 176 bytes --]
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH v5 0/4] gpio: mvebu: pwm fixes and improvements
2021-01-20 16:16 ` Baruch Siach
@ 2021-01-25 9:43 ` Bartosz Golaszewski
-1 siblings, 0 replies; 14+ messages in thread
From: Bartosz Golaszewski @ 2021-01-25 9:43 UTC (permalink / raw)
To: Baruch Siach
Cc: Thierry Reding, Uwe Kleine-König, Lee Jones, Linus Walleij,
Andrew Lunn, Gregory Clement, Russell King,
Sebastian Hesselbarth, Thomas Petazzoni, Chris Packham,
Sascha Hauer, Ralph Sennhauser, linux-pwm, linux-gpio, arm-soc
On Wed, Jan 20, 2021 at 5:16 PM 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.
>
> v5:
>
> * Drop a patch applied to the gpio tree
>
> * Fix patch 4/4 description typo (Uwe)
>
> * Reduce the number of multiplications (Uwe)
>
> * Add spaces around '+' (Uwe)
>
> * Use '1ULL' instead of explicit cast to reduce verbosity
>
> * Add Linus' Reviewed-by tags to patches that are unchanged since v2
>
> v4:
>
> * Take advantage of zero value being treated as 2^32 by hardware. Rewrite
> patch 5/5 (Uwe).
>
> v3:
>
> * Improve patch 3/5 description (Uwe)
>
> * Add more Reviewed-by tags from Uwe
>
> v2:
>
> Address Uwe Kleine-König comments.
>
> * Improve patch 1/5 summary line
>
> * Add more information to patch 1/5 description
>
> * Add more information to patch 2/5 description
>
> * Don't round period/duty_cycle up in .apply (patch 3/5)
>
> * Expand the comment in path 5/5 based on RMK's analysis of hardware
> behaviour
>
> * Add Uwe's Reviewed-by tags
>
> Baruch Siach (4):
> gpio: mvebu: improve pwm period calculation accuracy
> gpio: mvebu: make pwm .get_state closer to idempotent
> gpio: mvebu: don't limit pwm period/duty_cycle to UINT_MAX
> gpio: mvebu: improve handling of pwm zero on/off values
>
> drivers/gpio/gpio-mvebu.c | 47 +++++++++++++++++++++------------------
> 1 file changed, 25 insertions(+), 22 deletions(-)
>
> --
> 2.29.2
>
Series applied, thanks a lot for the improvements! And thanks to Uwe
and Russel for the reviews.
Bartosz
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH v5 0/4] gpio: mvebu: pwm fixes and improvements
@ 2021-01-25 9:43 ` Bartosz Golaszewski
0 siblings, 0 replies; 14+ messages in thread
From: Bartosz Golaszewski @ 2021-01-25 9:43 UTC (permalink / raw)
To: Baruch Siach
Cc: Andrew Lunn, Sascha Hauer, linux-pwm, Linus Walleij,
Chris Packham, Russell King, linux-gpio, Thierry Reding,
Thomas Petazzoni, Uwe Kleine-König, Ralph Sennhauser,
Lee Jones, Gregory Clement, arm-soc, Sebastian Hesselbarth
On Wed, Jan 20, 2021 at 5:16 PM 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.
>
> v5:
>
> * Drop a patch applied to the gpio tree
>
> * Fix patch 4/4 description typo (Uwe)
>
> * Reduce the number of multiplications (Uwe)
>
> * Add spaces around '+' (Uwe)
>
> * Use '1ULL' instead of explicit cast to reduce verbosity
>
> * Add Linus' Reviewed-by tags to patches that are unchanged since v2
>
> v4:
>
> * Take advantage of zero value being treated as 2^32 by hardware. Rewrite
> patch 5/5 (Uwe).
>
> v3:
>
> * Improve patch 3/5 description (Uwe)
>
> * Add more Reviewed-by tags from Uwe
>
> v2:
>
> Address Uwe Kleine-König comments.
>
> * Improve patch 1/5 summary line
>
> * Add more information to patch 1/5 description
>
> * Add more information to patch 2/5 description
>
> * Don't round period/duty_cycle up in .apply (patch 3/5)
>
> * Expand the comment in path 5/5 based on RMK's analysis of hardware
> behaviour
>
> * Add Uwe's Reviewed-by tags
>
> Baruch Siach (4):
> gpio: mvebu: improve pwm period calculation accuracy
> gpio: mvebu: make pwm .get_state closer to idempotent
> gpio: mvebu: don't limit pwm period/duty_cycle to UINT_MAX
> gpio: mvebu: improve handling of pwm zero on/off values
>
> drivers/gpio/gpio-mvebu.c | 47 +++++++++++++++++++++------------------
> 1 file changed, 25 insertions(+), 22 deletions(-)
>
> --
> 2.29.2
>
Series applied, thanks a lot for the improvements! And thanks to Uwe
and Russel for the reviews.
Bartosz
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 14+ messages in thread
end of thread, other threads:[~2021-01-26 5:25 UTC | newest]
Thread overview: 14+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-01-20 16:16 [PATCH v5 0/4] gpio: mvebu: pwm fixes and improvements Baruch Siach
2021-01-20 16:16 ` Baruch Siach
2021-01-20 16:16 ` [PATCH v5 1/4] gpio: mvebu: improve pwm period calculation accuracy Baruch Siach
2021-01-20 16:16 ` Baruch Siach
2021-01-20 16:16 ` [PATCH v5 2/4] gpio: mvebu: make pwm .get_state closer to idempotent Baruch Siach
2021-01-20 16:16 ` Baruch Siach
2021-01-20 16:16 ` [PATCH v5 3/4] gpio: mvebu: don't limit pwm period/duty_cycle to UINT_MAX Baruch Siach
2021-01-20 16:16 ` Baruch Siach
2021-01-20 16:16 ` [PATCH v5 4/4] gpio: mvebu: improve handling of pwm zero on/off values Baruch Siach
2021-01-20 16:16 ` Baruch Siach
2021-01-20 17:24 ` Uwe Kleine-König
2021-01-20 17:24 ` Uwe Kleine-König
2021-01-25 9:43 ` [PATCH v5 0/4] gpio: mvebu: pwm fixes and improvements Bartosz Golaszewski
2021-01-25 9:43 ` Bartosz Golaszewski
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