linux-kernel - Re: [PATCH] irqchip/renesas-intc-irqpin: Use platform_get_irq

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Date:   Thu, 16 Dec 2021 14:22:45 +0000
From:   "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] irqchip/renesas-intc-irqpin: Use platform_get_irq_optional()
 to get the interrupt

Hi Geert,

Thank you for the review.

On Thu, Dec 16, 2021 at 8:45 AM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>
> Hi Prabhakar,
>
> On Thu, Dec 16, 2021 at 12:45 AM Lad Prabhakar
> <prabhakar.mahadev-lad.rj@...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().
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
>
> > --- a/drivers/irqchip/irq-renesas-intc-irqpin.c
> > +++ b/drivers/irqchip/irq-renesas-intc-irqpin.c
>
> > @@ -418,12 +417,14 @@ static int intc_irqpin_probe(struct platform_device *pdev)
> >
> >         /* allow any number of IRQs between 1 and INTC_IRQPIN_MAX */
> >         for (k = 0; k < INTC_IRQPIN_MAX; k++) {
> > -               irq = platform_get_resource(pdev, IORESOURCE_IRQ, k);
> > -               if (!irq)
> > +               ret = platform_get_irq_optional(pdev, k);
> > +               if (ret == -EPROBE_DEFER)
> > +                       goto err0;
> > +               if (ret < 0)
> >                         break;
>
> Shouldn't all errors be considered fatal, except for -ENXIO (no
> interrupt)?
>
Initial behavior of this driver was even if one
platform_get_resource() succeeded the probe continued further, this is
the same behavior which I wanted to keep with this code while using
platform_get_irq_optional(). But as you pointed out I'll change it to below:

+               ret = platform_get_irq(pdev, k);
+               if (ret < 0)
+                       goto err0;

We bail out any error case and will also drop the check for (nirqs < 1).

Cheers,
Prabhakar
> >
> >                 p->irq[k].p = p;
> > -               p->irq[k].requested_irq = irq->start;
> > +               p->irq[k].requested_irq = ret;
> >         }
> >
> >         nirqs = k;
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds