linux-kernel - Re: [RFC PATCH] gpio/gpiolib: Forbid irqchip default trigger if probed over DT

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Date:   Thu, 8 Sep 2016 00:13:27 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Marc Zyngier <marc.zyngier@....com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] gpio/gpiolib: Forbid irqchip default trigger if
 probed over DT

On Tue, Sep 6, 2016 at 3:59 PM, Marc Zyngier <marc.zyngier@....com> wrote:

> Using a default trigger is a bad idea if using DT to configure
> interrupts, as the device's interrupt specifier will always contain
> the trigger configuration.
>
> Let's warn about that particular situation, and revert to not
> having a default. Hopefully, the couple of drivers still using
> this feature will quickly be fixed.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@....com>

Patch applied. This is a good way to get rid of this madness.

> +       /*
> +        * Specifying a default trigger is a terrible idea if DT is
> +        * used to configure the interrupts, as you may end-up with
> +        * conflicting triggers. Tell the user, and reset to NONE.
> +        */
> +       if (WARN_ON(of_node && type != IRQ_TYPE_NONE,
> +                   "%s: Ignoring %d default trigger\n", of_node->full_name))
> +               type = IRQ_TYPE_NONE;

I *strongly* suspect this is bad also when using ACPI.

Would the GPIO ACPI people devise a patch on top of this
to emit the same warning for the ACPI usecase?

Yours,
Linus Walleij