linux-kernel - Re: [PATCH v3 3/3] gpio: xilinx: Utilize generic bitmap_get_value and _set

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Date:   Sat, 27 Mar 2021 18:35:40 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     William Breathitt Gray <vilhelm.gray@...il.com>
Cc:     Syed Nayyar Waris <syednwaris@...il.com>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Michal Simek <michal.simek@...inx.com>,
        Arnd Bergmann <arnd@...db.de>,
        Robert Richter <rrichter@...vell.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Zhang, Rui" <rui.zhang@...el.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Amit Kucheria <amit.kucheria@...durent.com>,
        Linux-Arch <linux-arch@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        Linux PM <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v3 3/3] gpio: xilinx: Utilize generic bitmap_get_value and _set_value

On Sat, Mar 27, 2021 at 2:02 PM William Breathitt Gray
<vilhelm.gray@...il.com> wrote:
> On Sat, Mar 27, 2021 at 09:29:26AM +0200, Andy Shevchenko wrote:
> > On Saturday, March 27, 2021, Syed Nayyar Waris <syednwaris@...il.com> wrote:
> > > On Fri, Mar 26, 2021 at 11:32 PM Andy Shevchenko
> > > <andy.shevchenko@...il.com> wrote:
> > > > On Sat, Mar 6, 2021 at 4:08 PM Syed Nayyar Waris <syednwaris@...il.com>
> > > wrote:
> > > >
> > > > > +       bitmap_set_value(old, 64, state[0], 32, 0);
> > > > > +       bitmap_set_value(old, 64, state[1], 32, 32);
> > > >
> > > > Isn't it effectively bitnap_from_arr32() ?
> > > >
> > > > > +       bitmap_set_value(new, 64, state[0], 32, 0);
> > > > > +       bitmap_set_value(new, 64, state[1], 32, 32);
> > > >
> > > > Ditto.

> > > With bitmap_set_value() we are also specifying the offset (or start)
> > > position too. so that the remainder of the array remains unaffected. I
> > > think it would not be feasible to use bitmap_from/to_arr32()  here.
> >
> >
> > You have hard coded start and nbits parameters to 32. How is it not the
> > same?
>
> Would these four lines become something like this:
>
>         bitmap_from_arr32(old, state, 64);
>         ...
>         bitmap_from_arr32(new, state, 64);

This is my understanding, but I might miss something. I mean driver
specifics that make my proposal incorrect.

-- 
With Best Regards,
Andy Shevchenko