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

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Date:   Mon, 22 Nov 2021 14:10:32 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Marc Zyngier <maz@...nel.org>
Cc:     linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        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>,
        linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH] of/irq: Add a quirk for controllers with their own
 definition of interrupt-map

Hi Marc,

On Mon, Nov 22, 2021 at 11:30 AM 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>
> Signed-off-by: Marc Zyngier <maz@...nel.org>

Thanks for your patch!

> --- a/drivers/of/irq.c
> +++ b/drivers/of/irq.c
> @@ -76,6 +76,36 @@ struct device_node *of_irq_find_parent(struct device_node *child)
>  }
>  EXPORT_SYMBOL_GPL(of_irq_find_parent);
>
> +/*
> + * These interrupt controllers abuse interrupt-map for unspeakable
> + * reasons and rely on the core code to *ignore* it (the drivers do
> + * their own parsing of the property).
> + *
> + * If you think of adding to the list for something *new*, think
> + * again. There is a high chance that you will be sent back to the
> + * drawing board.
> + */
> +static const char * const of_irq_imap_abusers[] = {
> +       "CBEA,platform-spider-pic",
> +       "sti,platform-spider-pic",
> +       "realtek,rtl-intc",
> +       "fsl,ls1021a-extirq",
> +       "fsl,ls1043a-extirq",
> +       "fsl,ls1088a-extirq",
> +       "renesas,rza1-irqc",
> +};

Are you sure "renesas,rza1-irqc" handles this wrong? How should it
be handled instead? I read the other thread[1], but didn't became
any wiser: interrupts are mapped one-to-one with the RZ/A1 IRQC.

In both v5.15 and v5.16-rc1, interrupts seem to work fine on RSK+RZA1
and RZA2MEVB, both with gpio-keys and when used as a wake-up interrupt.

With this patch applied, I see double keypresses with evtest: when
pressing a key, I get a key-down event, immediately followed by a
key-up event. When releasing the key, I again get two events.

Good (v5.15 or v5.16-rc1):

    Event: time 1637585631.288990, type 1 (EV_KEY), code 2 (KEY_1), value 1
    Event: time 1637585631.288990, -------------- SYN_REPORT ------------
    Event: time 1637585631.499924, type 1 (EV_KEY), code 2 (KEY_1), value 0
    Event: time 1637585631.499924, -------------- SYN_REPORT ------------

Bad (v5.16-rc1 + this patch):

    Event: time 1637585341.946647, type 1 (EV_KEY), code 2 (KEY_1), value 1
    Event: time 1637585341.946647, -------------- SYN_REPORT ------------
    Event: time 1637585341.960256, type 1 (EV_KEY), code 2 (KEY_1), value 0
    Event: time 1637585341.960256, -------------- SYN_REPORT ------------
    Event: time 1637585342.146775, type 1 (EV_KEY), code 2 (KEY_1), value 1
    Event: time 1637585342.146775, -------------- SYN_REPORT ------------
    Event: time 1637585342.160092, type 1 (EV_KEY), code 2 (KEY_1), value 0
    Event: time 1637585342.160092, -------------- SYN_REPORT ------------

Thanks!

[1] https://lore.kernel.org/all/bbe5506a2458b2d6049bd22a5fda77ae6175ddec.camel@svanheule.net/

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