On 20/03/17 11:27, Eva Rachel Retuya wrote:
> 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>
I've applied this to the togreg branch of iio.git rather than sending
as a quick fix for the simple reason that nothing currently uses the
value once it has been computed that I can immediately see!
That whole chunk of code probably just wants to be ripped out in
the longer term.
Jonathan
> ---
> drivers/staging/iio/light/tsl2x7x_core.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/staging/iio/light/tsl2x7x_core.c b/drivers/staging/iio/light/tsl2x7x_core.c
> index ea15bc1..197201a 100644
> --- 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, int length,
> 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);
> }
>
> /**
>
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