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Date:   Mon, 9 Nov 2020 12:31:23 -0500
From:   William Breathitt Gray <vilhelm.gray@gmail.com>
To:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc:     Syed Nayyar Waris <syednwaris@gmail.com>,
        Arnd Bergmann <arnd@kernel.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Michal Simek <michal.simek@xilinx.com>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v12 4/4] gpio: xilinx: Utilize generic bitmap_get_value
 and _set_value
Message-ID: <20201109173107.GA14643@shinobu>
References: <15a044d3ba23f00c31fd09437bdd3e5924bb91cd.1603055402.git.syednwaris@gmail.com>
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On Mon, Nov 09, 2020 at 07:22:20PM +0200, Andy Shevchenko wrote:
> On Mon, Nov 09, 2020 at 12:11:40PM -0500, William Breathitt Gray wrote:
> > On Mon, Nov 09, 2020 at 10:15:29PM +0530, Syed Nayyar Waris wrote:
> > > On Mon, Nov 09, 2020 at 03:41:53PM +0100, Arnd Bergmann wrote:
>=20
> ...
>=20
> > >  static inline void bitmap_set_value(unsigned long *map,
> > > -                                    unsigned long value,
> > > +                                    unsigned long value, const size_=
t length,
> > >                                      unsigned long start, unsigned lo=
ng nbits)
> > >  {
> > >          const size_t index =3D BIT_WORD(start);
> > > @@ -15,6 +15,10 @@ static inline void bitmap_set_value(unsigned long =
*map,
> > >          } else {
> > >                  map[index + 0] &=3D ~BITMAP_FIRST_WORD_MASK(start);
> > >                  map[index + 0] |=3D value << offset;
> > > +
> > > +               if (index + 1 >=3D length)
> > > +                       __builtin_unreachable();
> > > +
> > >                  map[index + 1] &=3D ~BITMAP_LAST_WORD_MASK(start + n=
bits);
> > >                  map[index + 1] |=3D value >> space;
> > >          }
> >=20
> > Hi Syed,
> >=20
> > Let's rename 'length' to 'nbits' as Arnd suggested, and rename 'nbits'
> > to value_width.
>=20
> length here is in longs. I guess this is the point of entire patch.

Ah yes, this should become 'const unsigned long nbits' and represent the
length of the bitmap in bits and not longs.

> But to me sounds like it would be better to have simply bitmap_set_value6=
4() /
> bitmap_set_value32() with proper optimization done and forget about varia=
dic
> ones for now.

The gpio-xilinx driver can have arbitrary sizes for width[0] and
width[1], so unfortunately that means we don't know the start position
nor the width of the value beforehand.

William Breathitt Gray

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