On 2021-07-21 05:06, Liam Beguin wrote: > From: Liam Beguin <lvb@xxxxxxxxxx> > > The IIO_VAL_FRACTIONAL_LOG2 scale type doesn't return the expected > scale. Update the case so that the rescaler returns a fractional type > and a more precise scale. > > Signed-off-by: Liam Beguin <lvb@xxxxxxxxxx> > --- > drivers/iio/afe/iio-rescale.c | 9 +++------ > 1 file changed, 3 insertions(+), 6 deletions(-) > > diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c > index 35fa3b4e53e0..47cd4a6d9aca 100644 > --- a/drivers/iio/afe/iio-rescale.c > +++ b/drivers/iio/afe/iio-rescale.c > @@ -44,12 +44,9 @@ int rescale_process_scale(struct rescale *rescale, int scale_type, > *val2 = rescale->denominator; > return IIO_VAL_FRACTIONAL; > case IIO_VAL_FRACTIONAL_LOG2: > - tmp = *val * 1000000000LL; > - do_div(tmp, rescale->denominator); > - tmp *= rescale->numerator; > - do_div(tmp, 1000000000LL); > - *val = tmp; > - return scale_type; > + *val = rescale->numerator * *val; > + *val2 = rescale->denominator * (1 << *val2); > + return IIO_VAL_FRACTIONAL; Hi! I do not think this is an uncontested improvement. You have broken the case where *val2 is "large" before the scale factor is applied. Cheers, Peter > case IIO_VAL_INT_PLUS_NANO: > tmp = ((s64)*val * 1000000000LL + *val2) * rescale->numerator; > tmp = div_s64(tmp, rescale->denominator); >
