Date:   Wed, 22 Dec 2021 14:13:35 -0500
From:   Liam Beguin <liambeguin@gmail.com>
To:     Andy Shevchenko <andy.shevchenko@gmail.com>
Cc:     Peter Rosin <peda@axentia.se>, Jonathan Cameron <jic23@kernel.org>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-iio <linux-iio@vger.kernel.org>,
        devicetree <devicetree@vger.kernel.org>,
        Rob Herring <robh+dt@kernel.org>
Subject: Re: [PATCH v11 11/15] iio: test: add basic tests for the iio-rescale
 driver
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References: <20211222034646.222189-1-liambeguin@gmail.com>
 <20211222034646.222189-12-liambeguin@gmail.com>
 <CAHp75Ve4RuJLMdpdKe14nobuZHRNKA7tWt4yE82+noF5p+xxpw@mail.gmail.com>
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On Wed, Dec 22, 2021 at 02:38:13PM +0200, Andy Shevchenko wrote:
> On Wed, Dec 22, 2021 at 5:47 AM Liam Beguin <liambeguin@gmail.com> wrote:
> >
> > From: Liam Beguin <lvb@xiphos.com>
> >
> > The iio-rescale driver supports various combinations of scale types and
> > offsets. These can often result in large integer multiplications. Make
> > sure these calculations are done right by adding a set of kunit test
> > cases that build on top of iio-test-format.
> 
> ...
> 
> > +       int fract_mult = 100000000LL;
> 
> Perhaps also change to use the prefix?

Argh.. I missed this file. Sorry, will update.

> ...
> 
> > +       *nano = (s64)tmp * 10 * fract_mult + tmp2;
> 
> I'm also puzzled what the meaning of the 10 is here?

That comes from iio_str_to_fixpoint().
I sould've added a comment to make it more explicit as details escape me
right now...  Will fix.

> ...
> 
> > +       err = 1000000 * abs(exp - real);
> 
> Prefix?

Ok

> ...
> 
> > +       err = div64_u64(err, abs(exp));
> > +       return (int)err;
> 
> return div64_u64();

will do.

Cheers,
Liam

> -- 
> With Best Regards,
> Andy Shevchenko