linux-kernel - Re: [PATCH v3 4/5] gpio: gpiolib: Add ngirq member to struct gpio_irq

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Date:   Wed, 18 May 2022 19:30:02 +0100
From:   "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Phil Edworthy <phil.edworthy@...esas.com>,
        Biju Das <biju.das.jz@...renesas.com>
Subject: Re: [PATCH v3 4/5] gpio: gpiolib: Add ngirq member to struct gpio_irq_chip

Hi Geert,

Thank you for the review.

On Thu, May 12, 2022 at 8:29 AM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>
> Hi Prabhakar,
>
> On Wed, May 11, 2022 at 8:32 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 give 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>
>
> Thanks for your patch!
>
> > --- a/drivers/gpio/gpiolib.c
> > +++ b/drivers/gpio/gpiolib.c
> > @@ -1221,7 +1221,7 @@ static int gpiochip_hierarchy_add_domain(struct gpio_chip *gc)
> >         gc->irq.domain = irq_domain_create_hierarchy(
> >                 gc->irq.parent_domain,
> >                 0,
> > -               gc->ngpio,
> > +               gc->irq.ngirq ?: gc->ngpio,
> >                 gc->irq.fwnode,
> >                 &gc->irq.child_irq_domain_ops,
> >                 gc);
> > @@ -1574,7 +1574,7 @@ static int gpiochip_add_irqchip(struct gpio_chip *gc,
> >         } else {
> >                 /* Some drivers provide custom irqdomain ops */
> >                 gc->irq.domain = irq_domain_create_simple(fwnode,
> > -                       gc->ngpio,
> > +                       gc->irq.ngirq ?: gc->ngpio,
> >                         gc->irq.first,
> >                         gc->irq.domain_ops ?: &gpiochip_domain_ops,
> >                         gc);
>
> OK.
>
> gpiochip_irqchip_remove() does:
>
>         /* Remove all IRQ mappings and delete the domain */
>         if (gc->irq.domain) {
>                 unsigned int irq;
>
>                 for (offset = 0; offset < gc->ngpio; offset++) {
>                        if (!gpiochip_irqchip_irq_valid(gc, offset))
>
> Hence it relies on gc->irq.valid_mask, which I think is OK in general.
>
Agreed.

>                                 continue;
>
>                         irq = irq_find_mapping(gc->irq.domain, offset);
>                         irq_dispose_mapping(irq);
>                 }
>
>                 irq_domain_remove(gc->irq.domain);
>
>         }
>
> > --- a/include/linux/gpio/driver.h
> > +++ b/include/linux/gpio/driver.h
> > @@ -51,6 +51,14 @@ struct gpio_irq_chip {
> >          */
> >         const struct irq_domain_ops *domain_ops;
> >
> > +       /**
> > +        * @ngirq:
> > +        *
> > +        * The number of GPIO IRQ's handled by this IRQ domain; usually is
> > +        * equal to ngpio.
>
> "If not set, ngpio will be used."
>
sure will update the comment.

Cheers,
Prabhakar

> > +        */
> > +       u16 ngirq;
> > +
> >  #ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
> >         /**
> >          * @fwnode:
>
> 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