linux-kernel - Re: [PATCH v5 3/5] gpio: gpiolib: Allow free() callback to be overridden

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Date:   Tue, 24 May 2022 11:29:26 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     "Lad, Prabhakar" <prabhakar.csengg@...il.com>
Cc:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Marc Zyngier <maz@...nel.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Thomas Gleixner <tglx@...utronix.de>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        linux-tegra <linux-tegra@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Phil Edworthy <phil.edworthy@...esas.com>,
        Biju Das <biju.das.jz@...renesas.com>
Subject: Re: [PATCH v5 3/5] gpio: gpiolib: Allow free() callback to be overridden

On Tue, May 24, 2022 at 11:07 AM Lad, Prabhakar
<prabhakar.csengg@...il.com> wrote:
> On Tue, May 24, 2022 at 9:54 AM Linus Walleij <linus.walleij@...aro.org> wrote:
> >
> > On Mon, May 23, 2022 at 7:43 PM Lad Prabhakar
> > <prabhakar.mahadev-lad.rj@...renesas.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.
> > >
> > > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > > Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>
> >
> > So that function today looks like this:
> >
> > static void gpiochip_hierarchy_setup_domain_ops(struct irq_domain_ops *ops)
> > {
> >         ops->activate = gpiochip_irq_domain_activate;
> >         ops->deactivate = gpiochip_irq_domain_deactivate;
> >         ops->alloc = gpiochip_hierarchy_irq_domain_alloc;
> >         ops->free = irq_domain_free_irqs_common;
> >
> >         /*
> >          * We only allow overriding the translate() function for
> >          * hierarchical chips, and this should only be done if the user
> >          * really need something other than 1:1 translation.
> >          */
> >         if (!ops->translate)
> >                 ops->translate = gpiochip_hierarchy_irq_domain_translate;
> > }
> >
> > (...)
> > -       ops->free = irq_domain_free_irqs_common;
> > (...)
> > > +       if (!ops->free)
> > > +               ops->free = irq_domain_free_irqs_common;
> >
> > Marc Z is working on cleaning up the way that gpiolib is (ab)using
> > irqchips. We definitely need his ACK if we do things like this.
> > This doesn't look like one of the big offenders to me, but I want
> > to make sure we don't create new problems while Marc is trying
> > to solve the old ones.
> >
> Agreed, I had a discussion with Marc on v3 series [0].

Hm yeah I guess I am just stepping on Marc's toes with all my mails :(

I'll try to just wait for Marc's Reviewed-by instead and not add to the noise,
I'm probably just wrong.

Yours,
Linus Walleij