Re: [PATCH v13 06/11] iio: afe: rescale: make use of units.h

[Andy Shevchenko]

On Tue, Feb 1, 2022 at 3:59 AM Peter Rosin <peda@xxxxxxxxxx> wrote:
> On 2022-01-31 16:23, Andy Shevchenko wrote:
> > On Mon, Jan 31, 2022 at 4:50 PM Peter Rosin <peda@xxxxxxxxxx> wrote:
> >> On 2022-01-30 17:10, Liam Beguin wrote:
> >
> > ...
> >
> >>> -             tmp = div_s64_rem(tmp, 1000000000LL, &rem);
> >>> +             tmp = div_s64_rem(tmp, GIGA, &rem);
> >>
> >> It is NOT easy for me to say which of GIGA/NANO is most fitting.
> >
> > What do you mean? The idea behind is the use of the macro depending on
> > the actual power of 10 in use (taking into account the sign of the
> > exponent part).
> >
> >> There are a couple of considerations:
> >>
> >> A) 1000000000 is just a big value (GIGA fits). Something big is
> >>    needed to not lose too much precision.
> >
> > Does it have a physical meaning?
>
> No, this is just a scaling factor which is moments later
> eliminted by a matching inverse operation. It's math purely
> about attempting to preserve precision and has nothing to do
> with the units of the values that are involved.

I see your point now, shame on me.


-- 
With Best Regards,
Andy Shevchenko