[lm-sensors] [PATCH] pmbus: Use long variables for register to data

[lm-sensors] [PATCH] pmbus: Use long variables for register to data

[Guenter Roeck]

Using integer variable types for register to data conversions can cause
overflows especially for power calculations, which are in microwatt.
Use long variables instead.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
---
 drivers/hwmon/pmbus_core.c |   20 ++++++++++----------
 1 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/hwmon/pmbus_core.c b/drivers/hwmon/pmbus_core.c
index 744672c..8e31a8e 100644
--- a/drivers/hwmon/pmbus_core.c
+++ b/drivers/hwmon/pmbus_core.c
@@ -362,8 +362,8 @@ static struct pmbus_data *pmbus_update_device(struct device *dev)
  * Convert linear sensor values to milli- or micro-units
  * depending on sensor type.
  */
-static int pmbus_reg2data_linear(struct pmbus_data *data,
-				 struct pmbus_sensor *sensor)
+static long pmbus_reg2data_linear(struct pmbus_data *data,
+				  struct pmbus_sensor *sensor)
 {
 	s16 exponent;
 	s32 mantissa;
@@ -397,15 +397,15 @@ static int pmbus_reg2data_linear(struct pmbus_data *data,
 	else
 		val >>= -exponent;
 
-	return (int)val;
+	return val;
 }
 
 /*
  * Convert direct sensor values to milli- or micro-units
  * depending on sensor type.
  */
-static int pmbus_reg2data_direct(struct pmbus_data *data,
-				 struct pmbus_sensor *sensor)
+static long pmbus_reg2data_direct(struct pmbus_data *data,
+				  struct pmbus_sensor *sensor)
 {
 	long val = (s16) sensor->data;
 	long m, b, R;
@@ -440,12 +440,12 @@ static int pmbus_reg2data_direct(struct pmbus_data *data,
 		R++;
 	}
 
-	return (int)((val - b) / m);
+	return (val - b) / m;
 }
 
-static int pmbus_reg2data(struct pmbus_data *data, struct pmbus_sensor *sensor)
+static long pmbus_reg2data(struct pmbus_data *data, struct pmbus_sensor *sensor)
 {
-	int val;
+	long val;
 
 	if (data->info->direct[sensor->class])
 		val = pmbus_reg2data_direct(data, sensor);
@@ -619,7 +619,7 @@ static int pmbus_get_boolean(struct pmbus_data *data, int index, int *val)
 	if (!s1 && !s2)
 		*val = !!regval;
 	else {
-		int v1, v2;
+		long v1, v2;
 		struct pmbus_sensor *sensor1, *sensor2;
 
 		sensor1 = &data->sensors[s1];
@@ -661,7 +661,7 @@ static ssize_t pmbus_show_sensor(struct device *dev,
 	if (sensor->data < 0)
 		return sensor->data;
 
-	return snprintf(buf, PAGE_SIZE, "%d\n", pmbus_reg2data(data, sensor));
+	return snprintf(buf, PAGE_SIZE, "%ld\n", pmbus_reg2data(data, sensor));
 }
 
 static ssize_t pmbus_set_sensor(struct device *dev,
-- 
1.7.3.1


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Re: [lm-sensors] [PATCH] pmbus: Use long variables for register to

[Jean Delvare]

Hi Guenter,

On Mon, 11 Jul 2011 12:04:24 -0700, Guenter Roeck wrote:
> Using integer variable types for register to data conversions can cause
> overflows especially for power calculations, which are in microwatt.
> Use long variables instead.

I have no objection, using longs for calculations certainly makes
sense, however does it really help in practice? I thought that
sizeof(int) = sizeof(long) for all architectures on Linux?

> 
> Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>

Either way:

Acked-by: Jean Delvare <khali@linux-fr.org>

> ---
>  drivers/hwmon/pmbus_core.c |   20 ++++++++++----------
>  1 files changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/hwmon/pmbus_core.c b/drivers/hwmon/pmbus_core.c
> index 744672c..8e31a8e 100644
> --- a/drivers/hwmon/pmbus_core.c
> +++ b/drivers/hwmon/pmbus_core.c
> @@ -362,8 +362,8 @@ static struct pmbus_data *pmbus_update_device(struct device *dev)
>   * Convert linear sensor values to milli- or micro-units
>   * depending on sensor type.
>   */
> -static int pmbus_reg2data_linear(struct pmbus_data *data,
> -				 struct pmbus_sensor *sensor)
> +static long pmbus_reg2data_linear(struct pmbus_data *data,
> +				  struct pmbus_sensor *sensor)
>  {
>  	s16 exponent;
>  	s32 mantissa;
> @@ -397,15 +397,15 @@ static int pmbus_reg2data_linear(struct pmbus_data *data,
>  	else
>  		val >>= -exponent;
>  
> -	return (int)val;
> +	return val;
>  }
>  
>  /*
>   * Convert direct sensor values to milli- or micro-units
>   * depending on sensor type.
>   */
> -static int pmbus_reg2data_direct(struct pmbus_data *data,
> -				 struct pmbus_sensor *sensor)
> +static long pmbus_reg2data_direct(struct pmbus_data *data,
> +				  struct pmbus_sensor *sensor)
>  {
>  	long val = (s16) sensor->data;
>  	long m, b, R;
> @@ -440,12 +440,12 @@ static int pmbus_reg2data_direct(struct pmbus_data *data,
>  		R++;
>  	}
>  
> -	return (int)((val - b) / m);
> +	return (val - b) / m;
>  }
>  
> -static int pmbus_reg2data(struct pmbus_data *data, struct pmbus_sensor *sensor)
> +static long pmbus_reg2data(struct pmbus_data *data, struct pmbus_sensor *sensor)
>  {
> -	int val;
> +	long val;
>  
>  	if (data->info->direct[sensor->class])
>  		val = pmbus_reg2data_direct(data, sensor);
> @@ -619,7 +619,7 @@ static int pmbus_get_boolean(struct pmbus_data *data, int index, int *val)
>  	if (!s1 && !s2)
>  		*val = !!regval;
>  	else {
> -		int v1, v2;
> +		long v1, v2;
>  		struct pmbus_sensor *sensor1, *sensor2;
>  
>  		sensor1 = &data->sensors[s1];
> @@ -661,7 +661,7 @@ static ssize_t pmbus_show_sensor(struct device *dev,
>  	if (sensor->data < 0)
>  		return sensor->data;
>  
> -	return snprintf(buf, PAGE_SIZE, "%d\n", pmbus_reg2data(data, sensor));
> +	return snprintf(buf, PAGE_SIZE, "%ld\n", pmbus_reg2data(data, sensor));
>  }
>  
>  static ssize_t pmbus_set_sensor(struct device *dev,


-- 
Jean Delvare

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Re: [lm-sensors] [PATCH] pmbus: Use long variables for register to

[Guenter Roeck]

On Tue, Jul 12, 2011 at 03:00:16AM -0400, Jean Delvare wrote:
> Hi Guenter,
> 
> On Mon, 11 Jul 2011 12:04:24 -0700, Guenter Roeck wrote:
> > Using integer variable types for register to data conversions can cause
> > overflows especially for power calculations, which are in microwatt.
> > Use long variables instead.
> 
> I have no objection, using longs for calculations certainly makes
> sense, however does it really help in practice? I thought that
> sizeof(int) = sizeof(long) for all architectures on Linux?
> 
No ... for x86_64 long is 64 bit and int is 32 bit. I'll may have
to switch to "long long" at some point, though, or maybe s64.
Still hesitating to do that.

> > 
> > Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
> 
> Either way:
> 
> Acked-by: Jean Delvare <khali@linux-fr.org>
> 
Thanks,
Guenter

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Re: [lm-sensors] [PATCH] pmbus: Use long variables for register to

[Jean Delvare]

On Tue, 12 Jul 2011 06:40:57 -0700, Guenter Roeck wrote:
> On Tue, Jul 12, 2011 at 03:00:16AM -0400, Jean Delvare wrote:
> > Hi Guenter,
> > 
> > On Mon, 11 Jul 2011 12:04:24 -0700, Guenter Roeck wrote:
> > > Using integer variable types for register to data conversions can cause
> > > overflows especially for power calculations, which are in microwatt.
> > > Use long variables instead.
> > 
> > I have no objection, using longs for calculations certainly makes
> > sense, however does it really help in practice? I thought that
> > sizeof(int) = sizeof(long) for all architectures on Linux?
> > 
> No ... for x86_64 long is 64 bit and int is 32 bit.

D'oh, you're right. Will I ever remember this...

> I'll may have
> to switch to "long long" at some point, though, or maybe s64.
> Still hesitating to do that.

I'd think twice about it (and how to do it exactly)... I think long
long is relatively expensive on 32-bit x86?

-- 
Jean Delvare

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Re: [lm-sensors] [PATCH] pmbus: Use long variables for register to

[Guenter Roeck]

On Tue, Jul 12, 2011 at 12:03:25PM -0400, Jean Delvare wrote:
> On Tue, 12 Jul 2011 06:40:57 -0700, Guenter Roeck wrote:
> > On Tue, Jul 12, 2011 at 03:00:16AM -0400, Jean Delvare wrote:
> > > Hi Guenter,
> > > 
> > > On Mon, 11 Jul 2011 12:04:24 -0700, Guenter Roeck wrote:
> > > > Using integer variable types for register to data conversions can cause
> > > > overflows especially for power calculations, which are in microwatt.
> > > > Use long variables instead.
> > > 
> > > I have no objection, using longs for calculations certainly makes
> > > sense, however does it really help in practice? I thought that
> > > sizeof(int) = sizeof(long) for all architectures on Linux?
> > > 
> > No ... for x86_64 long is 64 bit and int is 32 bit.
> 
> D'oh, you're right. Will I ever remember this...
> 
> > I'll may have
> > to switch to "long long" at some point, though, or maybe s64.
> > Still hesitating to do that.
> 
> I'd think twice about it (and how to do it exactly)... I think long
> long is relatively expensive on 32-bit x86?
> 
That is my concern ... I think I'll wait with that change until someone
actually needs it.

Guenter

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