linux-kernel - Re: [PATCH v2 07/14] iio: sx9310: Use long instead of int for channel bitmaps

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Message-ID: <CAHp75Vc_3VYAkVcTCAXzqxqFnpQ4Qi=iPSFW_sUjYGO=o6YMtA@mail.gmail.com>
Date:   Wed, 29 Jul 2020 10:00:16 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     Daniel Campello <campello@...omium.org>,
        LKML <devicetree@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Douglas Anderson <dianders@...omium.org>,
        Enrico Granata <egranata@...omium.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        linux-iio <linux-iio@...r.kernel.org>
Subject: Re: [PATCH v2 07/14] iio: sx9310: Use long instead of int for channel bitmaps

On Wed, Jul 29, 2020 at 4:03 AM Stephen Boyd <swboyd@...omium.org> wrote:
> Quoting Daniel Campello (2020-07-28 16:05:13)
> > Uses for_each_set_bit() macro to loop over channel bitmaps.

...

> > +       unsigned long chan_prox_stat;
>
> This can be DECLARE_BITMAP(chan_prox_stat, SX9310_NUM_CHANNELS)

> > +       unsigned long chan_read;
> > +       unsigned long chan_event;
>
> Same for these?

...

> > +       prox_changed = (data->chan_prox_stat ^ val) & data->chan_event;
>
> I was expecting:
>
>
>         bitmap_xor(&prox_changed, &data->chan_prox_stat, &val, SX9310_NUM_CHANNELS);
>         bitmap_and(&prox_changed, &data->chan_event, SX9310_NUM_CHANNELS);

I agree with this. On a small number of channels (up to 32) it will be
reduced to simple operations, but will leave a possibility to have
more with easy redefine.

(though _and() above misses one argument AFAICT)

...

> > +       unsigned long channels = 0;
>
> Use DECLARE_BITMAP(channels, SX9310_NUM_CHANNELS)?


-- 
With Best Regards,
Andy Shevchenko