diff mbox

ACPI: Adjust Kelvin offset to match local implementation

Message ID 20090301140318.5cf56287@hyperion.delvare (mailing list archive)
State Accepted
Headers show

Commit Message

Jean Delvare March 1, 2009, 1:03 p.m. UTC 
The exact offset between Kelvin and degree Celsius is 273.15. However
ACPI handles temperature values with a single decimal place. As a
consequence, some implementations use an offset of 273.1 and others
use an offset of 273.2. Try to find out which one is being used, to
present the most accurate and visually appealing number.

Tested on a Sony Vaio PGC-GR214EP (which uses 273.1) and a Lenovo
Thinkpad T60p (which uses 273.2).

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Zhang Rui<rui.zhang@intel.com>
Cc: Len Brown <len.brown@intel.com>
---
Blame the mess on whoever decided that ACPI temperature would be
expressed in the least adapted unit in the world :(

Without this patch, I have the following sensors output:

acpitz-virtual-0
Adapter: Virtual device
temp1:       +44.9 C  (crit = +89.9 C)

With the patch I instead have:

acpitz-virtual-0
Adapter: Virtual device
temp1:       +45.0 C  (crit = +90.0 C)

Which I think is much easier to read.

 drivers/acpi/thermal.c |   42 +++++++++++++++++++++++++++++++++++-------
 1 file changed, 35 insertions(+), 7 deletions(-)

Comments

Zhang Rui March 3, 2009, 8:44 a.m. UTC | #1 
On Sun, 2009-03-01 at 21:03 +0800, Jean Delvare wrote:
> The exact offset between Kelvin and degree Celsius is 273.15. However
> ACPI handles temperature values with a single decimal place. As a
> consequence, some implementations use an offset of 273.1 and others
> use an offset of 273.2. Try to find out which one is being used, to
> present the most accurate and visually appealing number.
> 
> Tested on a Sony Vaio PGC-GR214EP (which uses 273.1) and a Lenovo
> Thinkpad T60p (which uses 273.2).
Sounds reasonable.

Acked-by: Zhang Rui <rui.zhang@intel.com>

> 
> Signed-off-by: Jean Delvare <khali@linux-fr.org>
> Cc: Zhang Rui<rui.zhang@intel.com>
> Cc: Len Brown <len.brown@intel.com>
> ---
> Blame the mess on whoever decided that ACPI temperature would be
> expressed in the least adapted unit in the world :(
> 
> Without this patch, I have the following sensors output:
> 
> acpitz-virtual-0
> Adapter: Virtual device
> temp1:       +44.9 C  (crit = +89.9 C)
> 
> With the patch I instead have:
> 
> acpitz-virtual-0
> Adapter: Virtual device
> temp1:       +45.0 C  (crit = +90.0 C)
> 
> Which I think is much easier to read.
> 
>  drivers/acpi/thermal.c |   42 +++++++++++++++++++++++++++++++++++-------
>  1 file changed, 35 insertions(+), 7 deletions(-)
> 
> --- linux-2.6.29-rc6.orig/drivers/acpi/thermal.c	2009-01-17 09:06:19.000000000 +0100
> +++ linux-2.6.29-rc6/drivers/acpi/thermal.c	2009-03-01 13:51:45.000000000 +0100
> @@ -193,6 +193,7 @@ struct acpi_thermal {
>  	struct timer_list timer;
>  	struct thermal_zone_device *thermal_zone;
>  	int tz_enabled;
> +	int kelvin_offset;
>  	struct mutex lock;
>  };
>  
> @@ -952,7 +953,7 @@ static void acpi_thermal_check(void *dat
>  }
>  
>  /* sys I/F for generic thermal sysfs support */
> -#define KELVIN_TO_MILLICELSIUS(t) (t * 100 - 273200)
> +#define KELVIN_TO_MILLICELSIUS(t, off) (((t) - (off)) * 100)
>  
>  static int thermal_get_temp(struct thermal_zone_device *thermal, char *buf)
>  {
> @@ -966,7 +967,8 @@ static int thermal_get_temp(struct therm
>  	if (result)
>  		return result;
>  
> -	return sprintf(buf, "%ld\n", KELVIN_TO_MILLICELSIUS(tz->temperature));
> +	return sprintf(buf, "%ld\n", KELVIN_TO_MILLICELSIUS(tz->temperature,
> +							    tz->kelvin_offset));
>  }
>  
>  static const char enabled[] = "kernel";
> @@ -1061,21 +1063,24 @@ static int thermal_get_trip_temp(struct
>  	if (tz->trips.critical.flags.valid) {
>  		if (!trip)
>  			return sprintf(buf, "%ld\n", KELVIN_TO_MILLICELSIUS(
> -				tz->trips.critical.temperature));
> +				tz->trips.critical.temperature,
> +				tz->kelvin_offset));
>  		trip--;
>  	}
>  
>  	if (tz->trips.hot.flags.valid) {
>  		if (!trip)
>  			return sprintf(buf, "%ld\n", KELVIN_TO_MILLICELSIUS(
> -					tz->trips.hot.temperature));
> +					tz->trips.hot.temperature,
> +					tz->kelvin_offset));
>  		trip--;
>  	}
>  
>  	if (tz->trips.passive.flags.valid) {
>  		if (!trip)
>  			return sprintf(buf, "%ld\n", KELVIN_TO_MILLICELSIUS(
> -					tz->trips.passive.temperature));
> +					tz->trips.passive.temperature,
> +					tz->kelvin_offset));
>  		trip--;
>  	}
>  
> @@ -1083,7 +1088,8 @@ static int thermal_get_trip_temp(struct
>  		tz->trips.active[i].flags.valid; i++) {
>  		if (!trip)
>  			return sprintf(buf, "%ld\n", KELVIN_TO_MILLICELSIUS(
> -					tz->trips.active[i].temperature));
> +					tz->trips.active[i].temperature,
> +					tz->kelvin_offset));
>  		trip--;
>  	}
>  
> @@ -1096,7 +1102,8 @@ static int thermal_get_crit_temp(struct
>  
>  	if (tz->trips.critical.flags.valid) {
>  		*temperature = KELVIN_TO_MILLICELSIUS(
> -				tz->trips.critical.temperature);
> +				tz->trips.critical.temperature,
> +				tz->kelvin_offset);
>  		return 0;
>  	} else
>  		return -EINVAL;
> @@ -1649,6 +1656,25 @@ static int acpi_thermal_get_info(struct
>  	return 0;
>  }
>  
> +/*
> + * The exact offset between Kelvin and degree Celsius is 273.15. However ACPI
> + * handles temperature values with a single decimal place. As a consequence,
> + * some implementations use an offset of 273.1 and others use an offset of
> + * 273.2. Try to find out which one is being used, to present the most
> + * accurate and visually appealing number.
> + *
> + * The heuristic below should work for all ACPI thermal zones which have a
> + * critical trip point with a value being a multiple of 0.5 degree Celsius.
> + */
> +static void acpi_thermal_guess_offset(struct acpi_thermal *tz)
> +{
> +	if (tz->trips.critical.flags.valid &&
> +	    (tz->trips.critical.temperature % 5) == 1)
> +		tz->kelvin_offset = 2731;
> +	else
> +		tz->kelvin_offset = 2732;
> +}
> +
>  static int acpi_thermal_add(struct acpi_device *device)
>  {
>  	int result = 0;
> @@ -1675,6 +1701,8 @@ static int acpi_thermal_add(struct acpi_
>  	if (result)
>  		goto free_memory;
>  
> +	acpi_thermal_guess_offset(tz);
> +
>  	result = acpi_thermal_register_thermal_zone(tz);
>  	if (result)
>  		goto free_memory;
> 
> 

--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Jean Delvare March 27, 2009, 9:55 a.m. UTC | #2 
Hi Rui,

On Tue, 03 Mar 2009 16:44:14 +0800, Zhang Rui wrote:
> On Sun, 2009-03-01 at 21:03 +0800, Jean Delvare wrote:
> > The exact offset between Kelvin and degree Celsius is 273.15. However
> > ACPI handles temperature values with a single decimal place. As a
> > consequence, some implementations use an offset of 273.1 and others
> > use an offset of 273.2. Try to find out which one is being used, to
> > present the most accurate and visually appealing number.
> > 
> > Tested on a Sony Vaio PGC-GR214EP (which uses 273.1) and a Lenovo
> > Thinkpad T60p (which uses 273.2).
> Sounds reasonable.
> 
> Acked-by: Zhang Rui <rui.zhang@intel.com>

Thanks. Is this patch queued for 2.6.30 somewhere?
Len Brown March 27, 2009, 3:52 p.m. UTC | #3 
On Fri, 27 Mar 2009, Jean Delvare wrote:

> Hi Rui,
> 
> On Tue, 03 Mar 2009 16:44:14 +0800, Zhang Rui wrote:
> > On Sun, 2009-03-01 at 21:03 +0800, Jean Delvare wrote:
> > > The exact offset between Kelvin and degree Celsius is 273.15. However
> > > ACPI handles temperature values with a single decimal place. As a
> > > consequence, some implementations use an offset of 273.1 and others
> > > use an offset of 273.2. Try to find out which one is being used, to
> > > present the most accurate and visually appealing number.
> > > 
> > > Tested on a Sony Vaio PGC-GR214EP (which uses 273.1) and a Lenovo
> > > Thinkpad T60p (which uses 273.2).
> > Sounds reasonable.
> > 
> > Acked-by: Zhang Rui <rui.zhang@intel.com>
> 
> Thanks. Is this patch queued for 2.6.30 somewhere?

it was, but I had a conflict between this an another and so I dropped this 
one until I could look at it - which I havn't yet.  If you'd like to do
it for me, rebase on top of the acpi test branch.

thanks,
Len Brown, Intel Open Source Technology Center
--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Jean Delvare April 6, 2009, 1:58 p.m. UTC | #4 
Hi Len,

Sorry for the late reply.

On Fri, 27 Mar 2009 11:52:04 -0400 (EDT), Len Brown wrote:
> 
> On Fri, 27 Mar 2009, Jean Delvare wrote:
> 
> > Hi Rui,
> > 
> > On Tue, 03 Mar 2009 16:44:14 +0800, Zhang Rui wrote:
> > > On Sun, 2009-03-01 at 21:03 +0800, Jean Delvare wrote:
> > > > The exact offset between Kelvin and degree Celsius is 273.15. However
> > > > ACPI handles temperature values with a single decimal place. As a
> > > > consequence, some implementations use an offset of 273.1 and others
> > > > use an offset of 273.2. Try to find out which one is being used, to
> > > > present the most accurate and visually appealing number.
> > > > 
> > > > Tested on a Sony Vaio PGC-GR214EP (which uses 273.1) and a Lenovo
> > > > Thinkpad T60p (which uses 273.2).
> > > Sounds reasonable.
> > > 
> > > Acked-by: Zhang Rui <rui.zhang@intel.com>
> > 
> > Thanks. Is this patch queued for 2.6.30 somewhere?
> 
> it was, but I had a conflict between this an another and so I dropped this 
> one until I could look at it - which I havn't yet.  If you'd like to do
> it for me, rebase on top of the acpi test branch.

OK, I have rebased my patch against 2.6.29-git13 (which I seem to
understand contains the latest ACPI code), tested it and it looks OK.
I'll post the updated patch in a minute.

Thanks,
diff mbox

Patch

--- linux-2.6.29-rc6.orig/drivers/acpi/thermal.c	2009-01-17 09:06:19.000000000 +0100
+++ linux-2.6.29-rc6/drivers/acpi/thermal.c	2009-03-01 13:51:45.000000000 +0100
@@ -193,6 +193,7 @@  struct acpi_thermal {
 	struct timer_list timer;
 	struct thermal_zone_device *thermal_zone;
 	int tz_enabled;
+	int kelvin_offset;
 	struct mutex lock;
 };
 
@@ -952,7 +953,7 @@  static void acpi_thermal_check(void *dat
 }
 
 /* sys I/F for generic thermal sysfs support */
-#define KELVIN_TO_MILLICELSIUS(t) (t * 100 - 273200)
+#define KELVIN_TO_MILLICELSIUS(t, off) (((t) - (off)) * 100)
 
 static int thermal_get_temp(struct thermal_zone_device *thermal, char *buf)
 {
@@ -966,7 +967,8 @@  static int thermal_get_temp(struct therm
 	if (result)
 		return result;
 
-	return sprintf(buf, "%ld\n", KELVIN_TO_MILLICELSIUS(tz->temperature));
+	return sprintf(buf, "%ld\n", KELVIN_TO_MILLICELSIUS(tz->temperature,
+							    tz->kelvin_offset));
 }
 
 static const char enabled[] = "kernel";
@@ -1061,21 +1063,24 @@  static int thermal_get_trip_temp(struct
 	if (tz->trips.critical.flags.valid) {
 		if (!trip)
 			return sprintf(buf, "%ld\n", KELVIN_TO_MILLICELSIUS(
-				tz->trips.critical.temperature));
+				tz->trips.critical.temperature,
+				tz->kelvin_offset));
 		trip--;
 	}
 
 	if (tz->trips.hot.flags.valid) {
 		if (!trip)
 			return sprintf(buf, "%ld\n", KELVIN_TO_MILLICELSIUS(
-					tz->trips.hot.temperature));
+					tz->trips.hot.temperature,
+					tz->kelvin_offset));
 		trip--;
 	}
 
 	if (tz->trips.passive.flags.valid) {
 		if (!trip)
 			return sprintf(buf, "%ld\n", KELVIN_TO_MILLICELSIUS(
-					tz->trips.passive.temperature));
+					tz->trips.passive.temperature,
+					tz->kelvin_offset));
 		trip--;
 	}
 
@@ -1083,7 +1088,8 @@  static int thermal_get_trip_temp(struct
 		tz->trips.active[i].flags.valid; i++) {
 		if (!trip)
 			return sprintf(buf, "%ld\n", KELVIN_TO_MILLICELSIUS(
-					tz->trips.active[i].temperature));
+					tz->trips.active[i].temperature,
+					tz->kelvin_offset));
 		trip--;
 	}
 
@@ -1096,7 +1102,8 @@  static int thermal_get_crit_temp(struct
 
 	if (tz->trips.critical.flags.valid) {
 		*temperature = KELVIN_TO_MILLICELSIUS(
-				tz->trips.critical.temperature);
+				tz->trips.critical.temperature,
+				tz->kelvin_offset);
 		return 0;
 	} else
 		return -EINVAL;
@@ -1649,6 +1656,25 @@  static int acpi_thermal_get_info(struct
 	return 0;
 }
 
+/*
+ * The exact offset between Kelvin and degree Celsius is 273.15. However ACPI
+ * handles temperature values with a single decimal place. As a consequence,
+ * some implementations use an offset of 273.1 and others use an offset of
+ * 273.2. Try to find out which one is being used, to present the most
+ * accurate and visually appealing number.
+ *
+ * The heuristic below should work for all ACPI thermal zones which have a
+ * critical trip point with a value being a multiple of 0.5 degree Celsius.
+ */
+static void acpi_thermal_guess_offset(struct acpi_thermal *tz)
+{
+	if (tz->trips.critical.flags.valid &&
+	    (tz->trips.critical.temperature % 5) == 1)
+		tz->kelvin_offset = 2731;
+	else
+		tz->kelvin_offset = 2732;
+}
+
 static int acpi_thermal_add(struct acpi_device *device)
 {
 	int result = 0;
@@ -1675,6 +1701,8 @@  static int acpi_thermal_add(struct acpi_
 	if (result)
 		goto free_memory;
 
+	acpi_thermal_guess_offset(tz);
+
 	result = acpi_thermal_register_thermal_zone(tz);
 	if (result)
 		goto free_memory;