| Date | Thu, 22 Apr 2010 12:54:01 -0700 | From | Greg KH <> | Subject | [064/139] hwmon: (sht15) Fix sht15_calc_temp interpolation function |
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2.6.33-stable review patch. If anyone has any objections, please let us know.
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From: Jerome Oufella <jerome.oufella@savoirfairelinux.com>
commit 328a2c22abd08911e37fa66f1358f829cecd72e9 upstream.
I discovered two issues. First the previous sht15_calc_temp() loop did not iterate through the temppoints array since the (data->supply_uV > temppoints[i - 1].vdd) test is always true in this direction.
Also the two-points linear interpolation function was returning biased values due to a stray division by 1000 which shouldn't be there.
[JD: Also change the default value for d1 from 0 to something saner.]
Signed-off-by: Jerome Oufella <jerome.oufella@savoirfairelinux.com> Acked-by: Jonathan Cameron <jic23@cam.ac.uk> Signed-off-by: Jean Delvare <khali@linux-fr.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- drivers/hwmon/sht15.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- a/drivers/hwmon/sht15.c +++ b/drivers/hwmon/sht15.c @@ -302,13 +302,13 @@ error_ret: **/ static inline int sht15_calc_temp(struct sht15_data *data) { - int d1 = 0; + int d1 = temppoints[0].d1; int i; - for (i = 1; i < ARRAY_SIZE(temppoints); i++) + for (i = ARRAY_SIZE(temppoints) - 1; i > 0; i--) /* Find pointer to interpolate */ if (data->supply_uV > temppoints[i - 1].vdd) { - d1 = (data->supply_uV/1000 - temppoints[i - 1].vdd) + d1 = (data->supply_uV - temppoints[i - 1].vdd) * (temppoints[i].d1 - temppoints[i - 1].d1) / (temppoints[i].vdd - temppoints[i - 1].vdd) + temppoints[i - 1].d1;
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