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From:   "Lad, Prabhakar" <prabhakar.csengg@gmail.com>
Date:   Sat, 25 Dec 2021 17:27:45 +0000
Message-ID: <CA+V-a8t1myOt0rhJExem_T2tJUM3PLL9KuXn0=_LtucJPHLkbA@mail.gmail.com>
Subject: Re: [PATCH] irqchip/renesas-irqc: Use platform_get_irq_optional() to
 get the interrupt
To:     Andy Shevchenko <andy.shevchenko@gmail.com>
Cc:     Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Marc Zyngier <maz@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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Hi Andy,

Thank you for the review.

On Sat, Dec 25, 2021 at 4:46 PM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
>
> On Thu, Dec 16, 2021 at 9:52 AM Lad Prabhakar
> <prabhakar.mahadev-lad.rj@bp.renesas.com> wrote:
> >
> > platform_get_resource(pdev, IORESOURCE_IRQ, ..) relies on static
> > allocation of IRQ resources in DT core code, this causes an issue
> > when using hierarchical interrupt domains using "interrupts" property
> > in the node as this bypassed the hierarchical setup and messed up the
> > irq chaining.
> >
> > In preparation for removal of static setup of IRQ resource from DT core
> > code use platform_get_irq_optional().
>
>
> > +               ret = platform_get_irq_optional(pdev, k);
> > +               if (ret == -EPROBE_DEFER)
> > +                       goto err_runtime_pm_disable;
> > +               if (ret < 0)
> >                         break;
>
> The best approach is
>
> ret = platform_get_irq_optional(...);
> if (ret < 0 && ret != -ENXIO)
>   return ret;
> if (ret > 0)
>   ...we got it...
>
> It will allow the future API fix of platform_get_irq_optional() to be
> really optional.
>
Later patch [0] (merged into -next) does check for -ENXIO first.

[0] https://lore.kernel.org/lkml/20211216182121.5323-1-prabhakar.mahadev-lad.rj@bp.renesas.com/t/

Cheers,
Prabhakar