On Fri Jul 23, 2021 at 5:20 PM EDT, Peter Rosin wrote: > 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! Hi Peter, > > I do not think this is an uncontested improvement. You have broken the > case > where *val2 is "large" before the scale factor is applied. I was a little reluctant to add this change as I keep increasing the scope of this series, but since I added tests for all cases, I didn't want to leave this one out. Would you rather I drop this patch and the test cases associated to it? Thanks, Liam > > Cheers, > Peter > > > case IIO_VAL_INT_PLUS_NANO: > > tmp = ((s64)*val * 1000000000LL + *val2) * rescale->numerator; > > tmp = div_s64(tmp, rescale->denominator); > >
