linux-kernel - Re: [PATCH v4 3/7] gpio: gpiolib: Add ngirq member to struct gpio_irq

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Message-ID: <CACRpkda1pfL8tk0S_0bHvj4kWYrLTTeOz3b_A9qK5DJwHWeTXw@mail.gmail.com>
Date:   Thu, 19 May 2022 15:26:16 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Cc:     Marc Zyngier <maz@...nel.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Thomas Gleixner <tglx@...utronix.de>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        linux-gpio@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Prabhakar <prabhakar.csengg@...il.com>,
        linux-renesas-soc@...r.kernel.org,
        Phil Edworthy <phil.edworthy@...esas.com>,
        Biju Das <biju.das.jz@...renesas.com>
Subject: Re: [PATCH v4 3/7] gpio: gpiolib: Add ngirq member to struct gpio_irq_chip

On Wed, May 18, 2022 at 9:30 PM Lad Prabhakar
<prabhakar.mahadev-lad.rj@...renesas.com> wrote:

> Supported GPIO IRQs by the chip is not always equal to the number of GPIO
> pins. For example on Renesas RZ/G2L SoC where it has GPIO0-122 pins but at
> a given point a maximum of only 32 GPIO pins can be used as IRQ lines in
> the IRQC domain.
>
> This patch adds ngirq member to struct gpio_irq_chip and passes this as a
> size to irq_domain_create_hierarchy()/irq_domain_create_simple() if it is
> being set in the driver otherwise fallbacks to using ngpio.
>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>

NAK

As pointed out this is a property of the hardware and thus you should
derive this property of the hardware from the compatible string.

For example by passing per-variant .data in struct of_device_id.

Unique hardware properties means unique hardware means it should
have a unique compatible string. Otherwise something is wrong
with the compatibles.

Yours,
Linus Walleij