linux-kernel - Re: [PATCH v2 5/9] iio: inkern: Add a helper to query an available minimum raw value

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Date:   Mon, 5 Jun 2023 12:45:24 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Herve Codina <herve.codina@...tlin.com>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>,
        alsa-devel@...a-project.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v2 5/9] iio: inkern: Add a helper to query an available
 minimum raw value

On Mon, Jun 5, 2023 at 10:46 AM Herve Codina <herve.codina@...tlin.com> wrote:
> On Sat, 3 Jun 2023 17:04:37 +0300
> andy.shevchenko@...il.com wrote:
> > Tue, May 23, 2023 at 05:12:19PM +0200, Herve Codina kirjoitti:

...

> > > +           case IIO_VAL_INT:
> > > +                   *val = vals[--length];
> >
> > > +                   while (length) {
> >
> >                       while (length--) {
> >
> > will do the job and at the same time...
> >
> > > +                           if (vals[--length] < *val)
> > > +                                   *val = vals[length];
> >
> > ...this construction becomes less confusing (easier to parse).
>
> Indeed, I will change in the next iteration.

And looking into above line, this whole construction I would prefer to
have a macro in minmax.h like

#define min_array(array, len) \
{( \
  typeof(len) __len = (len); \
  typeof(*(array)) __element = (array)[--__len]; \
  while (__len--) \
    __element = min(__element, (array)[__len]); \
  __element; \
)}

(it might need more work, but you got the idea)

> > > +                   }
> > > +                   break;

...

> > > +           default:
> > > +                   /* FIXME: learn about min for other iio values */
> >
> > I believe in a final version this comment won't be here.
>
> We have the same FIXME comment in the iio_channel_read_max() function I
> copied to create this iio_channel_read_min() and, to be honest, I
> don't really know how to handle these other cases.
>
> In this series, I would prefer to keep this FIXME.

I see, Jonathan needs to be involved here then.

> > > +                   return -EINVAL;

-- 
With Best Regards,
Andy Shevchenko