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

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Message-ID: <YapRL+2gQBjNyK4p@robh.at.kernel.org>
Date:   Fri, 3 Dec 2021 11:17:35 -0600
From:   Rob Herring <robh@...nel.org>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Marc Zyngier <maz@...nel.org>,
        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>,
        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

On Thu, Dec 02, 2021 at 04:06:21PM +0100, Geert Uytterhoeven wrote:
> 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

and 'platforms'. Will fixup.

> 
> > +                * 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(...)

Why? Then we are comparing intc twice because we still need it for the 
intc && !imap case.
> 
> > +               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
>