linux-kernel - Re: [PATCH 2/3] drivers: iio: adc: LTC2499 support

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Date:   Tue, 23 Aug 2022 18:21:56 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Jonathan Cameron <jic23@...nel.org>
Cc:     Ciprian Regus <ciprian.regus@...log.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        linux-iio <linux-iio@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
Subject: Re: [PATCH 2/3] drivers: iio: adc: LTC2499 support

On Mon, Aug 22, 2022 at 11:13 PM Jonathan Cameron <jic23@...nel.org> wrote:
> On Mon, 22 Aug 2022 15:51:05 +0300
> Ciprian Regus <ciprian.regus@...log.com> wrote:

In reply to Jonathan's comments to answer his question and add more
comments from me.

...

> > Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/2499fe.pdf
> >
> > Signed-off-by: Ciprian Regus <ciprian.regus@...log.com>

Tag block mustn't have the blank line(s).

...

> >  #include <linux/iio/iio.h>
> >  #include <linux/iio/driver.h>
> >  #include <linux/module.h>
> > +#include <linux/property.h>
> why?

device_get_match_data() requires it.

But why not sort them?

> >  #include <linux/mod_devicetable.h>

...

> > -             *val = (be32_to_cpu(st->buf) >> 14) - (1 << 17);
>
> Old code here is less than ideal, should be reading into 3 bytes then using
> the be24 accesors. Please fix whilst here.  You will need multiple paths here
> depending on size.
>
> > +             *val = (be32_to_cpu(st->buf) >> st->sub_lsb) -
> > +                     BIT(ddata->chip_info->resolution + 1);

Shouldn't this use some kind of sign_extend()?

Also with a temporary variable for chip info this line can be single.

   struct ... *ci = ddata->chip_info;

   ...BIT(ci->resolution + 1)

...

> > +     u32 resolution;

Keep this in a way that the "longer lines go first".

...

> > +     resolution = st->common_ddata.chip_info->resolution;
> > +     st->sub_lsb = 31 - (resolution + 1);
> > +     st->recv_size = resolution / BITS_PER_BYTE + 1;

BITS_TO_BYTES()

...

> >  static const struct i2c_device_id ltc2497_id[] = {
> > -     { "ltc2497", 0 },
> > +     { "ltc2497", TYPE_LTC2497 },
> > +     { "ltc2499", TYPE_LTC2499 },

Use pointers here like you have done for the OF table.

> >       { }
> >  };

...

> > +enum chip_type {
> > +     TYPE_LTC2496,
> > +     TYPE_LTC2497,
> > +     TYPE_LTC2499

Keep trailing comma.

> > +};

-- 
With Best Regards,
Andy Shevchenko