linux-kernel - Re: [PATCH v2] of/irq: Add a quirk for controllers with their own definition of interrupt-map

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Date:   Thu, 2 Dec 2021 16:06:21 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Marc Zyngier <maz@...nel.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Android Kernel Team <kernel-team@...roid.com>,
        Rob Herring <robh@...nel.org>, John Crispin <john@...ozen.org>,
        Biwen Li <biwen.li@....com>,
        Chris Brandt <chris.brandt@...esas.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Sander Vanheule <sander@...nheule.net>
Subject: Re: [PATCH v2] of/irq: Add a quirk for controllers with their own
 definition of interrupt-map

Hi Marc,

On Wed, Dec 1, 2021 at 12:41 PM Marc Zyngier <maz@...nel.org> wrote:
> Since 041284181226 ("of/irq: Allow matching of an interrupt-map local
> to an interrupt controller"), a handful of interrupt controllers have
> stopped working correctly. This is due to the DT exposing a non-sensical
> interrupt-map property, and their drivers relying on the kernel ignoring
> this property.
>
> Since we cannot realistically fix this terrible behaviour, add a quirk
> for the limited set of devices that have implemented this monster,
> and document that this is a pretty bad practice.
>
> Cc: Rob Herring <robh@...nel.org>
> Cc: John Crispin <john@...ozen.org>
> Cc: Biwen Li <biwen.li@....com>
> Cc: Chris Brandt <chris.brandt@...esas.com>
> Cc: Geert Uytterhoeven <geert+renesas@...der.be>
> Cc: Sander Vanheule <sander@...nheule.net>
> Signed-off-by: Marc Zyngier <maz@...nel.org>
> ---
>
> Notes:
>     v2: Switched over to of_device_compatible_match() as per Rob's
>         request.

Thanks for the update!

> --- a/drivers/of/irq.c
> +++ b/drivers/of/irq.c

> @@ -159,12 +179,16 @@ int of_irq_parse_raw(const __be32 *addr, struct of_phandle_args *out_irq)
>                 /*
>                  * Now check if cursor is an interrupt-controller and
>                  * if it is then we are done, unless there is an
> -                * interrupt-map which takes precedence.
> +                * interrupt-map which takes precedence if we're not
> +                * in presence of once of these broken platform that

one

> +                * want to parse interrupt-map themselves for $reason.
>                  */
>                 bool intc = of_property_read_bool(ipar, "interrupt-controller");
> +               bool imap_abuse;
>
>                 imap = of_get_property(ipar, "interrupt-map", &imaplen);
> -               if (imap == NULL && intc) {
> +               imap_abuse = imap && of_device_compatible_match(ipar, of_irq_imap_abusers);

... = intc && imap && of_device_compatible_match(...)

> +               if (intc && (imap == NULL || imap_abuse)) {
>                         pr_debug(" -> got it !\n");
>                         return 0;
>                 }

Still working fine on RZ/A1, so
Tested-by: Geert Uytterhoeven <geert+renesas@...der.be>

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