Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 27 Apr 2023 12:37:33 +0200
From:   Andreas Kemnade <andreas@kemnade.info>
To:     Christophe Leroy <christophe.leroy@csgroup.eu>
Cc:     Andy Shevchenko <andy.shevchenko@gmail.com>,
        "linus.walleij@linaro.org" <linus.walleij@linaro.org>,
        "brgl@bgdev.pl" <brgl@bgdev.pl>,
        "linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        ": Tony Lindgren" <tony@atomide.com>,
        Aaro Koskinen <aaro.koskinen@iki.fi>,
        "linux-omap@vger.kernel.org" <linux-omap@vger.kernel.org>
Subject: Re: [PATCH] gpiolib: fix allocation of mixed dynamic/static GPIOs
Message-ID: <20230427123733.15ad4aa3@aktux>
In-Reply-To: <52453352-74bd-979f-03b6-322489800538@csgroup.eu>
References: <20230426220338.430638-1-andreas@kemnade.info>
        <f6b261ad-3267-db70-c173-154a12c42bea@csgroup.eu>
        <CAHp75Vep8VSirY7mvGGCubNi-O4jS_inTALS3Ei9mQu98RV+7Q@mail.gmail.com>
        <52453352-74bd-979f-03b6-322489800538@csgroup.eu>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Thu, 27 Apr 2023 06:20:34 +0000
Christophe Leroy <christophe.leroy@csgroup.eu> wrote:

> Le 27/04/2023 =C3=A0 08:00, Andy Shevchenko a =C3=A9crit=C2=A0:
> > On Thu, Apr 27, 2023 at 8:40=E2=80=AFAM Christophe Leroy
> > <christophe.leroy@csgroup.eu> wrote: =20
> >>
> >>
> >>
> >> Le 27/04/2023 =C3=A0 00:03, Andreas Kemnade a =C3=A9crit : =20
> >>> [Vous ne recevez pas souvent de courriers de andreas@kemnade.info. D=
=C3=A9couvrez pourquoi ceci est important =C3=A0 https://aka.ms/LearnAboutS=
enderIdentification ]
> >>>
> >>> If static allocation and dynamic allocation GPIOs are present,
> >>> dynamic allocation pollutes the numberspace for static allocation,
> >>> causing static allocation to fail.
> >>> Enfore dynamic allocation above GPIO_DYNAMIC_BASE. =20
> >>
> >> Hum ....
> >>
> >> Commit 7b61212f2a07 ("gpiolib: Get rid of ARCH_NR_GPIOS") was supposed
> >> to enforce dynamic allocation above GPIO_DYNAMIC_BASE already.
> >>
> >> Can you describe what is going wrong exactly with the above commit ? =
=20
> >=20
> > Above commit only works to the first dynamic allocation, if you need
> > more than one with static ones present it mistakenly will give you a
> > base _below_ DYNAMIC_BASE. =20
>=20
> Ah right, that needs to be fixed.
>=20
> >=20
> > However, this change is just PoC I proposed, the conditional and
> > action should be slightly different to cover a corner case, when
> > statically allocated chip overlaps the DYNAMIC_BASE, i.e. gdev->base <
> > DYNAMIC_BASE, while gdev->base + gdev->ngpio >=3D DYNAMIC_BASE.
> >  =20
>=20
> Yes you are right, that's gdev->base + gdev->ngpio that should be checked.
>=20
and that not with simple continue or base might simply stay at DYNAMIC_BASE.

I will send a v2 of this patch with refined logic.

Regards,
Andreas