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

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Message-ID: <20230605161129.4ac3231b@bootlin.com>
Date:   Mon, 5 Jun 2023 16:11:29 +0200
From:   Herve Codina <herve.codina@...tlin.com>
To:     Andy Shevchenko <andy.shevchenko@...il.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

Hi Andy,

On Mon, 5 Jun 2023 12:45:24 +0300
Andy Shevchenko <andy.shevchenko@...il.com> wrote:

> 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)

I will also introduce max_array() and update both iio_channel_read_max()
and iio_channel_read_min() to use these macros.

Will be available in the next series iteration.

Thanks,
Hervé

> 
> > > > +                   }
> > > > +                   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;  
>