hwmon: (sht15) Fix integer overflow in humidity calculation
An integer overflow occurs in the calculation of RHlinear when the
relative humidity is greater than around 30%. The consequence is a subtle
(but noticeable) error in the resulting humidity measurement.
Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: stable@kernel.org
Cc: Jonathan Cameron <jic23@cam.ac.uk>
diff --git a/drivers/hwmon/sht15.c b/drivers/hwmon/sht15.c
index 3ba7dd82..1a9c32d 100644
--- a/drivers/hwmon/sht15.c
+++ b/drivers/hwmon/sht15.c
@@ -333,11 +333,11 @@
const int c1 = -4;
const int c2 = 40500; /* x 10 ^ -6 */
- const int c3 = -2800; /* x10 ^ -9 */
+ const int c3 = -28; /* x 10 ^ -7 */
RHlinear = c1*1000
+ c2 * data->val_humid/1000
- + (data->val_humid * data->val_humid * c3)/1000000;
+ + (data->val_humid * data->val_humid * c3) / 10000;
return (temp - 25000) * (10000 + 80 * data->val_humid)
/ 1000000 + RHlinear;
}