linux-kernel - Re: [PATCH v7 3/5] gpio: gpiolib: Allow free() callback to be overridden

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Date:   Wed, 06 Jul 2022 08:01:08 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     "Lad, Prabhakar" <prabhakar.csengg@...il.com>
Cc:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        devicetree <devicetree@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Biju Das <biju.das.jz@...renesas.com>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH v7 3/5] gpio: gpiolib: Allow free() callback to be overridden

On Tue, 05 Jul 2022 05:53:03 +0100,
"Lad, Prabhakar" <prabhakar.csengg@...il.com> wrote:
> 
> On Mon, Jul 4, 2022 at 5:16 PM Andy Shevchenko
> <andy.shevchenko@...il.com> wrote:
> >
> > On Sun, Jul 3, 2022 at 9:43 PM Lad Prabhakar <prabhakar.csengg@...il.com> wrote:
> > >
> > > Allow free() callback to be overridden from irq_domain_ops for
> > > hierarchical chips.
> > >
> > > This allows drivers to free up resources which are allocated during
> > > child_to_parent_hwirq()/populate_parent_alloc_arg() callbacks.
> > >
> > > On Renesas RZ/G2L platform a bitmap is maintained for TINT slots, a slot
> > > is allocated in child_to_parent_hwirq() callback which is freed up in free
> > > callback hence this override.
> >
> > Hmm... To me this sounds asymmetrical. We alloc something in another
> > callback, which is not what this free is for. Perhaps it should be an
> > optional
> >
> > free_populated_parent_arg() or alike?
> >
> @Marc your thoughts?

I think there are enough optional callbacks, and we don't currently
have a clear picture of how this may be used in the future, specially
based on a sample of *one*.

Let's get it in as is, and tweak things as we go, should another user
require a slightly different behaviour. This also saves us the debate
around the naming, which is always pretty useless.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.