linux-kernel - Re: [PATCH 3/3] iio: addac: ad74413r: correct comparator gpio getters mask usage

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Date:   Sun, 9 Jan 2022 14:13:05 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Cosmin Tanislav <demonsingur@...il.com>
Cc:     cosmin.tanislav@...log.com, Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        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>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>
Subject: Re: [PATCH 3/3] iio: addac: ad74413r: correct comparator gpio getters
 mask usage

On Fri, Jan 7, 2022 at 7:34 AM Cosmin Tanislav <demonsingur@...il.com> wrote:
>
> The value of the GPIOs is currently altered using offsets rather
> than masks. Make use the BIT macro to turn the offsets into masks.

of the

...

> -       status &= AD74413R_DIN_COMP_OUT_SHIFT_X(real_offset);
> +       status &= BIT(real_offset);

But this is completely different.

> +       bitmap_zero(bits, chip->ngpio);
> +
>         for_each_set_bit(offset, mask, chip->ngpio) {
>                 unsigned int real_offset = st->comp_gpio_offsets[offset];
>
>                 if (val & BIT(real_offset))
> -                       *bits |= offset;
> +                       *bits |= BIT(offset);

So, how was it working before? If it fixes, it should go with the
Fixes tag and before patch 2.

>         }

On top of that, you may try to see if one of bitmap_*() APIs can be
suitable here to perform the above in a more optimal way.
(At least this conditional can be replaced with __asign_bit() call,
but I think refactoring the entire loop may reveal a better approach)

-- 
With Best Regards,
Andy Shevchenko