Re: [PATCH 4/9] sh: intc: Drop the use of irq_create_identity_mapping()

From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Marc Zyngier <maz@kernel.org>
Cc: Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"open list:BROADCOM NVRAM DRIVER" <linux-mips@vger.kernel.org>,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
	Linux-sh list <linux-sh@vger.kernel.org>,
	Daniel Mack <daniel@zonque.org>,
	Robert Jarzmik <robert.jarzmik@free.fr>,
	Haojian Zhuang <haojian.zhuang@gmail.com>,
	Yoshinori Sato <ysato@users.sourceforge.jp>,
	Rich Felker <dalias@libc.org>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 4/9] sh: intc: Drop the use of irq_create_identity_mapping()
Date: Tue, 6 Apr 2021 12:32:13 +0200	[thread overview]
Message-ID: <CAMuHMdU3vo1AWuDr69WK8-1w38+Q7KturAoL=cFpspZiYr2ssA@mail.gmail.com> (raw)
In-Reply-To: <20210406093557.1073423-5-maz@kernel.org>

Hi Marc,

On Tue, Apr 6, 2021 at 11:44 AM Marc Zyngier <maz@kernel.org> wrote:
> Instead of playing games with using irq_create_identity_mapping()
> and irq_domain_associate(), drop the use of the former and only
> use the latter, together with the allocation of the irq_desc
> as needed.
>
> It doesn't make the code less awful, but at least the intent
> is clearer.
>
> Signed-off-by: Marc Zyngier <maz@kernel.org>

Thanks for your patch!

> --- a/drivers/sh/intc/core.c
> +++ b/drivers/sh/intc/core.c
> @@ -179,6 +179,23 @@ static unsigned int __init save_reg(struct intc_desc_int *d,
>         return 0;
>  }
>
> +static bool __init intc_map(struct irq_domain *domain, int irq)
> +{
> +       int res;

warning: unused variable ‘res’ [-Wunused-variable]

> +
> +       if (!irq_to_desc(irq) && irq_alloc_desc_at(irq, NUMA_NO_NODE) != irq) {
> +               pr_err("uname to allocate IRQ %d\n", irq);
> +               return false;
> +       }
> +
> +       if (irq_domain_associate(domain, irq, irq)) {
> +               pr_err("domain association failure\n");
> +               return false;
> +       }
> +
> +       return true;
> +}
> +
>  int __init register_intc_controller(struct intc_desc *desc)
>  {
>         unsigned int i, k, smp;
> @@ -316,19 +333,8 @@ int __init register_intc_controller(struct intc_desc *desc)

warning: unused variable ‘res’ [-Wunused-variable]

>                 if (!vect->enum_id)
>                         continue;
>
> -               res = irq_create_identity_mapping(d->domain, irq);

> -               if (unlikely(res)) {
> -                       if (res == -EEXIST) {
> -                               res = irq_domain_associate(d->domain, irq, irq);
> -                               if (unlikely(res)) {
> -                                       pr_err("domain association failure\n");
> -                                       continue;
> -                               }
> -                       } else {
> -                               pr_err("can't identity map IRQ %d\n", irq);
> -                               continue;
> -                       }
> -               }
> +               if (!intc_map(d->domain, irq))
> +                       continue;
>
>                 intc_irq_xlate_set(irq, vect->enum_id, d);
>                 intc_register_irq(desc, d, vect->enum_id, irq);

Otherwise this seems to work fine on real hardware (landisk) and qemu
(rts7751r2d).  I did verify that the new function intc_map() is called.

Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-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