[PATCH 3.16 017/134] staging: iio: tsl2x7x_core: Fix standard deviation calculation

Ben Hutchings
2017-08-18T13:13:20Z

From: Eva Rachel Retuya <eraretuya@gmail.com>

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@cs.utah.edu>
Signed-off-by: Eva Rachel Retuya <eraretuya@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
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
@@ -849,7 +849,7 @@ 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);
}

/**