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 [off-list ref] wrote:

quoted

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@kernel.org>
Cc: John Crispin <john@phrozen.org>
Cc: Biwen Li <redacted>
Cc: Chris Brandt <chris.brandt@renesas.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Sander Vanheule <sander@svanheule.net>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---

Notes:
    v2: Switched over to of_device_compatible_match() as per Rob's
        request.

Thanks for the update!

quoted

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

quoted

@@ -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.

quoted

+                * 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.

quoted

+               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@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