[PATCH 4.11 38/78] staging: iio: tsl2x7x_core: Fix standard deviation calculation

[Greg Kroah-Hartman]

4.11-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eva Rachel Retuya <eraretuya@xxxxxxxxx>

commit cf6c77323a96fc40309cc8a4921ef206cccdd961 upstream.

Standard deviation is calculated as the square root of the variance
where variance is the mean of sample_sum and length. Correct the
computation of statP->stddev in accordance to the proper calculation.

Fixes: 3c97c08b5735 ("staging: iio: add TAOS tsl2x7x driver")
Reported-by: Abhiram Balasubramanian <abhiram@xxxxxxxxxxx>
Signed-off-by: Eva Rachel Retuya <eraretuya@xxxxxxxxx>
Signed-off-by: Jonathan Cameron <jic23@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/staging/iio/light/tsl2x7x_core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/staging/iio/light/tsl2x7x_core.c
+++ b/drivers/staging/iio/light/tsl2x7x_core.c
@@ -854,7 +854,7 @@ void tsl2x7x_prox_calculate(int *data, i
 		tmp = data[i] - statP->mean;
 		sample_sum += tmp * tmp;
 	}
-	statP->stddev = int_sqrt((long)sample_sum) / length;
+	statP->stddev = int_sqrt((long)sample_sum / length);
 }
 
 /**