All of lore.kernel.org
 help / color / mirror / Atom feed
* [PATCH] iio: stm32 trigger: fix sampling_frequency read
@ 2017-04-07 11:53 ` Fabrice Gasnier
  0 siblings, 0 replies; 6+ messages in thread
From: Fabrice Gasnier @ 2017-04-07 11:53 UTC (permalink / raw)
  To: jic23, linux, robh+dt, linux-arm-kernel, devicetree, linux-kernel
  Cc: linux-iio, mark.rutland, mcoquelin.stm32, alexandre.torgue, lars,
	knaack.h, pmeerw, fabrice.gasnier, benjamin.gaignard,
	benjamin.gaignard

When prescaler (PSC) is 0, it means div factor is 1: counter clock
frequency is equal to input clk / (PSC + 1).
When reload value is 8 for example, counter counts 9 cycles, from 0 to 8.
This is handled in frequency write routine, by writing respectively:
- prescaler - 1 to PSC
- reload value - 1 to ARR
This fix does the opposite when reading the frequency from PSC and ARR:
- prescaler is PSC + 1
- reload value is ARR + 1

Thus, PSC may be 0, depending on requested sampling frequency (div 1).
In this case, reading freq wrongly reports 0, instead of computing and
reporting correct value.
Remove test on !psc and !arr.

Small test on stm32f4 (example on tim1_trgo), before this fix:
$ cd /sys/bus/iio/devices/triggerX
$ echo 10000 > sampling_frequency
$ cat sampling_frequency
0

After this fix:
$ echo 10000 > sampling_frequency
$ cat sampling_frequency
10000

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
 drivers/iio/trigger/stm32-timer-trigger.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/trigger/stm32-timer-trigger.c b/drivers/iio/trigger/stm32-timer-trigger.c
index 994b96d..5ee362b 100644
--- a/drivers/iio/trigger/stm32-timer-trigger.c
+++ b/drivers/iio/trigger/stm32-timer-trigger.c
@@ -152,10 +152,10 @@ static ssize_t stm32_tt_read_frequency(struct device *dev,
 	regmap_read(priv->regmap, TIM_PSC, &psc);
 	regmap_read(priv->regmap, TIM_ARR, &arr);
 
-	if (psc && arr && (cr1 & TIM_CR1_CEN)) {
+	if (cr1 & TIM_CR1_CEN) {
 		freq = (unsigned long long)clk_get_rate(priv->clk);
-		do_div(freq, psc);
-		do_div(freq, arr);
+		do_div(freq, psc + 1);
+		do_div(freq, arr + 1);
 	}
 
 	return sprintf(buf, "%d\n", (unsigned int)freq);
-- 
1.9.1

^ permalink raw reply related	[flat|nested] 6+ messages in thread
* [PATCH] iio: stm32 trigger: fix sampling_frequency read
@ 2017-04-07 11:53 ` Fabrice Gasnier
  0 siblings, 0 replies; 6+ messages in thread
From: Fabrice Gasnier @ 2017-04-07 11:53 UTC (permalink / raw)
  To: jic23-DgEjT+Ai2ygdnm+yROfE0A, linux-I+IVW8TIWO2tmTQ+vhA3Yw,
	robh+dt-DgEjT+Ai2ygdnm+yROfE0A,
	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r,
	devicetree-u79uwXL29TY76Z2rM5mHXA,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA
  Cc: linux-iio-u79uwXL29TY76Z2rM5mHXA, mark.rutland-5wv7dgnIgG8,
	mcoquelin.stm32-Re5JQEeQqe8AvxtiuMwx3w,
	alexandre.torgue-qxv4g6HH51o, lars-Qo5EllUWu/uELgA04lAiVw,
	knaack.h-Mmb7MZpHnFY, pmeerw-jW+XmwGofnusTnJN9+BGXg,
	fabrice.gasnier-qxv4g6HH51o,
	benjamin.gaignard-QSEj5FYQhm4dnm+yROfE0A,
	benjamin.gaignard-qxv4g6HH51o

When prescaler (PSC) is 0, it means div factor is 1: counter clock
frequency is equal to input clk / (PSC + 1).
When reload value is 8 for example, counter counts 9 cycles, from 0 to 8.
This is handled in frequency write routine, by writing respectively:
- prescaler - 1 to PSC
- reload value - 1 to ARR
This fix does the opposite when reading the frequency from PSC and ARR:
- prescaler is PSC + 1
- reload value is ARR + 1

Thus, PSC may be 0, depending on requested sampling frequency (div 1).
In this case, reading freq wrongly reports 0, instead of computing and
reporting correct value.
Remove test on !psc and !arr.

Small test on stm32f4 (example on tim1_trgo), before this fix:
$ cd /sys/bus/iio/devices/triggerX
$ echo 10000 > sampling_frequency
$ cat sampling_frequency
0

After this fix:
$ echo 10000 > sampling_frequency
$ cat sampling_frequency
10000

Signed-off-by: Fabrice Gasnier <fabrice.gasnier-qxv4g6HH51o@public.gmane.org>
---
 drivers/iio/trigger/stm32-timer-trigger.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/trigger/stm32-timer-trigger.c b/drivers/iio/trigger/stm32-timer-trigger.c
index 994b96d..5ee362b 100644
--- a/drivers/iio/trigger/stm32-timer-trigger.c
+++ b/drivers/iio/trigger/stm32-timer-trigger.c
@@ -152,10 +152,10 @@ static ssize_t stm32_tt_read_frequency(struct device *dev,
 	regmap_read(priv->regmap, TIM_PSC, &psc);
 	regmap_read(priv->regmap, TIM_ARR, &arr);
 
-	if (psc && arr && (cr1 & TIM_CR1_CEN)) {
+	if (cr1 & TIM_CR1_CEN) {
 		freq = (unsigned long long)clk_get_rate(priv->clk);
-		do_div(freq, psc);
-		do_div(freq, arr);
+		do_div(freq, psc + 1);
+		do_div(freq, arr + 1);
 	}
 
 	return sprintf(buf, "%d\n", (unsigned int)freq);
-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

^ permalink raw reply related	[flat|nested] 6+ messages in thread
* [PATCH] iio: stm32 trigger: fix sampling_frequency read
@ 2017-04-07 11:53 ` Fabrice Gasnier
  0 siblings, 0 replies; 6+ messages in thread
From: Fabrice Gasnier @ 2017-04-07 11:53 UTC (permalink / raw)
  To: linux-arm-kernel

When prescaler (PSC) is 0, it means div factor is 1: counter clock
frequency is equal to input clk / (PSC + 1).
When reload value is 8 for example, counter counts 9 cycles, from 0 to 8.
This is handled in frequency write routine, by writing respectively:
- prescaler - 1 to PSC
- reload value - 1 to ARR
This fix does the opposite when reading the frequency from PSC and ARR:
- prescaler is PSC + 1
- reload value is ARR + 1

Thus, PSC may be 0, depending on requested sampling frequency (div 1).
In this case, reading freq wrongly reports 0, instead of computing and
reporting correct value.
Remove test on !psc and !arr.

Small test on stm32f4 (example on tim1_trgo), before this fix:
$ cd /sys/bus/iio/devices/triggerX
$ echo 10000 > sampling_frequency
$ cat sampling_frequency
0

After this fix:
$ echo 10000 > sampling_frequency
$ cat sampling_frequency
10000

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
 drivers/iio/trigger/stm32-timer-trigger.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/trigger/stm32-timer-trigger.c b/drivers/iio/trigger/stm32-timer-trigger.c
index 994b96d..5ee362b 100644
--- a/drivers/iio/trigger/stm32-timer-trigger.c
+++ b/drivers/iio/trigger/stm32-timer-trigger.c
@@ -152,10 +152,10 @@ static ssize_t stm32_tt_read_frequency(struct device *dev,
 	regmap_read(priv->regmap, TIM_PSC, &psc);
 	regmap_read(priv->regmap, TIM_ARR, &arr);
 
-	if (psc && arr && (cr1 & TIM_CR1_CEN)) {
+	if (cr1 & TIM_CR1_CEN) {
 		freq = (unsigned long long)clk_get_rate(priv->clk);
-		do_div(freq, psc);
-		do_div(freq, arr);
+		do_div(freq, psc + 1);
+		do_div(freq, arr + 1);
 	}
 
 	return sprintf(buf, "%d\n", (unsigned int)freq);
-- 
1.9.1

^ permalink raw reply related	[flat|nested] 6+ messages in thread
* Re: [PATCH] iio: stm32 trigger: fix sampling_frequency read
@ 2017-04-19  8:30   ` Benjamin Gaignard
  0 siblings, 0 replies; 6+ messages in thread
From: Benjamin Gaignard @ 2017-04-19  8:30 UTC (permalink / raw)
  To: Fabrice Gasnier
  Cc: Jonathan Cameron, Russell King - ARM Linux, Rob Herring,
	linux-arm-kernel, devicetree, Linux Kernel Mailing List,
	linux-iio, Mark Rutland, Maxime Coquelin, Alexandre Torgue,
	Lars-Peter Clausen, Hartmut Knaack, Peter Meerwald-Stadler,
	Benjamin GAIGNARD

2017-04-07 13:53 GMT+02:00 Fabrice Gasnier <fabrice.gasnier@st.com>:
> When prescaler (PSC) is 0, it means div factor is 1: counter clock
> frequency is equal to input clk / (PSC + 1).
> When reload value is 8 for example, counter counts 9 cycles, from 0 to 8.
> This is handled in frequency write routine, by writing respectively:
> - prescaler - 1 to PSC
> - reload value - 1 to ARR
> This fix does the opposite when reading the frequency from PSC and ARR:
> - prescaler is PSC + 1
> - reload value is ARR + 1
>
> Thus, PSC may be 0, depending on requested sampling frequency (div 1).
> In this case, reading freq wrongly reports 0, instead of computing and
> reporting correct value.
> Remove test on !psc and !arr.
>
> Small test on stm32f4 (example on tim1_trgo), before this fix:
> $ cd /sys/bus/iio/devices/triggerX
> $ echo 10000 > sampling_frequency
> $ cat sampling_frequency
> 0
>
> After this fix:
> $ echo 10000 > sampling_frequency
> $ cat sampling_frequency
> 10000
>
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
> ---
>  drivers/iio/trigger/stm32-timer-trigger.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iio/trigger/stm32-timer-trigger.c b/drivers/iio/trigger/stm32-timer-trigger.c
> index 994b96d..5ee362b 100644
> --- a/drivers/iio/trigger/stm32-timer-trigger.c
> +++ b/drivers/iio/trigger/stm32-timer-trigger.c
> @@ -152,10 +152,10 @@ static ssize_t stm32_tt_read_frequency(struct device *dev,
>         regmap_read(priv->regmap, TIM_PSC, &psc);
>         regmap_read(priv->regmap, TIM_ARR, &arr);
>
> -       if (psc && arr && (cr1 & TIM_CR1_CEN)) {
> +       if (cr1 & TIM_CR1_CEN) {
>                 freq = (unsigned long long)clk_get_rate(priv->clk);
> -               do_div(freq, psc);
> -               do_div(freq, arr);
> +               do_div(freq, psc + 1);
> +               do_div(freq, arr + 1);
>         }
>
>         return sprintf(buf, "%d\n", (unsigned int)freq);
> --
> 1.9.1
>
Acked-by: Benjamin Gaignard <benjamin.gaignard@st.com>

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] iio: stm32 trigger: fix sampling_frequency read
@ 2017-04-19  8:30   ` Benjamin Gaignard
  0 siblings, 0 replies; 6+ messages in thread
From: Benjamin Gaignard @ 2017-04-19  8:30 UTC (permalink / raw)
  To: Fabrice Gasnier
  Cc: Jonathan Cameron, Russell King - ARM Linux, Rob Herring,
	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r,
	devicetree-u79uwXL29TY76Z2rM5mHXA, Linux Kernel Mailing List,
	linux-iio-u79uwXL29TY76Z2rM5mHXA, Mark Rutland, Maxime Coquelin,
	Alexandre Torgue, Lars-Peter Clausen, Hartmut Knaack,
	Peter Meerwald-Stadler, Benjamin GAIGNARD

2017-04-07 13:53 GMT+02:00 Fabrice Gasnier <fabrice.gasnier-qxv4g6HH51o@public.gmane.org>:
> When prescaler (PSC) is 0, it means div factor is 1: counter clock
> frequency is equal to input clk / (PSC + 1).
> When reload value is 8 for example, counter counts 9 cycles, from 0 to 8.
> This is handled in frequency write routine, by writing respectively:
> - prescaler - 1 to PSC
> - reload value - 1 to ARR
> This fix does the opposite when reading the frequency from PSC and ARR:
> - prescaler is PSC + 1
> - reload value is ARR + 1
>
> Thus, PSC may be 0, depending on requested sampling frequency (div 1).
> In this case, reading freq wrongly reports 0, instead of computing and
> reporting correct value.
> Remove test on !psc and !arr.
>
> Small test on stm32f4 (example on tim1_trgo), before this fix:
> $ cd /sys/bus/iio/devices/triggerX
> $ echo 10000 > sampling_frequency
> $ cat sampling_frequency
> 0
>
> After this fix:
> $ echo 10000 > sampling_frequency
> $ cat sampling_frequency
> 10000
>
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier-qxv4g6HH51o@public.gmane.org>
> ---
>  drivers/iio/trigger/stm32-timer-trigger.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iio/trigger/stm32-timer-trigger.c b/drivers/iio/trigger/stm32-timer-trigger.c
> index 994b96d..5ee362b 100644
> --- a/drivers/iio/trigger/stm32-timer-trigger.c
> +++ b/drivers/iio/trigger/stm32-timer-trigger.c
> @@ -152,10 +152,10 @@ static ssize_t stm32_tt_read_frequency(struct device *dev,
>         regmap_read(priv->regmap, TIM_PSC, &psc);
>         regmap_read(priv->regmap, TIM_ARR, &arr);
>
> -       if (psc && arr && (cr1 & TIM_CR1_CEN)) {
> +       if (cr1 & TIM_CR1_CEN) {
>                 freq = (unsigned long long)clk_get_rate(priv->clk);
> -               do_div(freq, psc);
> -               do_div(freq, arr);
> +               do_div(freq, psc + 1);
> +               do_div(freq, arr + 1);
>         }
>
>         return sprintf(buf, "%d\n", (unsigned int)freq);
> --
> 1.9.1
>
Acked-by: Benjamin Gaignard <benjamin.gaignard-qxv4g6HH51o@public.gmane.org>

^ permalink raw reply	[flat|nested] 6+ messages in thread
* [PATCH] iio: stm32 trigger: fix sampling_frequency read
@ 2017-04-19  8:30   ` Benjamin Gaignard
  0 siblings, 0 replies; 6+ messages in thread
From: Benjamin Gaignard @ 2017-04-19  8:30 UTC (permalink / raw)
  To: linux-arm-kernel

2017-04-07 13:53 GMT+02:00 Fabrice Gasnier <fabrice.gasnier@st.com>:
> When prescaler (PSC) is 0, it means div factor is 1: counter clock
> frequency is equal to input clk / (PSC + 1).
> When reload value is 8 for example, counter counts 9 cycles, from 0 to 8.
> This is handled in frequency write routine, by writing respectively:
> - prescaler - 1 to PSC
> - reload value - 1 to ARR
> This fix does the opposite when reading the frequency from PSC and ARR:
> - prescaler is PSC + 1
> - reload value is ARR + 1
>
> Thus, PSC may be 0, depending on requested sampling frequency (div 1).
> In this case, reading freq wrongly reports 0, instead of computing and
> reporting correct value.
> Remove test on !psc and !arr.
>
> Small test on stm32f4 (example on tim1_trgo), before this fix:
> $ cd /sys/bus/iio/devices/triggerX
> $ echo 10000 > sampling_frequency
> $ cat sampling_frequency
> 0
>
> After this fix:
> $ echo 10000 > sampling_frequency
> $ cat sampling_frequency
> 10000
>
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
> ---
>  drivers/iio/trigger/stm32-timer-trigger.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iio/trigger/stm32-timer-trigger.c b/drivers/iio/trigger/stm32-timer-trigger.c
> index 994b96d..5ee362b 100644
> --- a/drivers/iio/trigger/stm32-timer-trigger.c
> +++ b/drivers/iio/trigger/stm32-timer-trigger.c
> @@ -152,10 +152,10 @@ static ssize_t stm32_tt_read_frequency(struct device *dev,
>         regmap_read(priv->regmap, TIM_PSC, &psc);
>         regmap_read(priv->regmap, TIM_ARR, &arr);
>
> -       if (psc && arr && (cr1 & TIM_CR1_CEN)) {
> +       if (cr1 & TIM_CR1_CEN) {
>                 freq = (unsigned long long)clk_get_rate(priv->clk);
> -               do_div(freq, psc);
> -               do_div(freq, arr);
> +               do_div(freq, psc + 1);
> +               do_div(freq, arr + 1);
>         }
>
>         return sprintf(buf, "%d\n", (unsigned int)freq);
> --
> 1.9.1
>
Acked-by: Benjamin Gaignard <benjamin.gaignard@st.com>

^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2017-04-19  8:30 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-04-07 11:53 [PATCH] iio: stm32 trigger: fix sampling_frequency read Fabrice Gasnier
2017-04-07 11:53 ` Fabrice Gasnier
2017-04-07 11:53 ` Fabrice Gasnier
2017-04-19  8:30 ` Benjamin Gaignard
2017-04-19  8:30   ` Benjamin Gaignard
2017-04-19  8:30   ` Benjamin Gaignard

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.