linux-kernel - Re: [PATCH] gpio: aggregator: Add interrupt support

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Date:   Mon, 4 Oct 2021 16:20:30 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Geert Uytterhoeven <geert+renesas@...der.be>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Viresh Kumar <viresh.kumar@...aro.org>, Enrico@....of.borg,
        Weigelt@....of.borg, metux IT consult <lkml@...ux.net>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Arnd Bergmann <arnd@...nel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        virtualization@...ts.linux-foundation.org,
        stratos-dev@...lists.linaro.org
Subject: Re: [PATCH] gpio: aggregator: Add interrupt support

On Mon, Oct 4, 2021 at 3:45 PM Geert Uytterhoeven
<geert+renesas@...der.be> wrote:
>
> Currently the GPIO Aggregator does not support interrupts.  This means
> that kernel drivers going from a GPIO to an IRQ using gpiod_to_irq(),
> and userspace applications using line events do not work.
>
> Add interrupt support by providing a gpio_chip.to_irq() callback, which
> just calls into the parent GPIO controller.
>
> Note that this does not implement full interrupt controller (irq_chip)
> support, so using e.g. gpio-keys with "interrupts" instead of "gpios"
> still does not work.

...

> @@ -414,7 +421,8 @@ static struct gpiochip_fwd *gpiochip_fwd_create(struct device *dev,
>         for (i = 0; i < ngpios; i++) {
>                 struct gpio_chip *parent = gpiod_to_chip(descs[i]);
>
> -               dev_dbg(dev, "%u => gpio-%d\n", i, desc_to_gpio(descs[i]));
> +               dev_dbg(dev, "%u => gpio %d irq %d\n", i,
> +                       desc_to_gpio(descs[i]), gpiod_to_irq(descs[i]));

This is an unconditional call that will allocate the IRQ descriptor
even if we don't use it. Correct?
If so, I don't like this.

-- 
With Best Regards,
Andy Shevchenko