linux-kernel - Re: [PATCH v2] gpiolib: Fix GPIO chip IRQ initialization restriction

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Message-ID: <CAHp75Vdbq3uHOyrfT-KFYRSj6v+s9GgOQjQ9a8mGn-4HSCpB9Q@mail.gmail.com>
Date:   Wed, 7 Jun 2023 17:12:01 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Jiawen Wu <jiawenwu@...stnetic.com>,
        Michael Walle <michael@...le.cc>
Cc:     linus.walleij@...aro.org, brgl@...ev.pl,
        shreeya.patel@...labora.com, linux-gpio@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] gpiolib: Fix GPIO chip IRQ initialization restriction

+Cc: Michael

On Wed, Jun 7, 2023 at 11:20 AM Jiawen Wu <jiawenwu@...stnetic.com> wrote:
>
> In case of gpio-regmap, IRQ chip is added by regmap-irq and associated with
> GPIO chip by gpiochip_irqchip_add_domain(). The initialization flag was not
> added in gpiochip_irqchip_add_domain(), causing gpiochip_to_irq() to return
> -EPROBE_DEFER.

Makes sense to me.
FWIW,
Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>

But it would be nice to hear from Michael about this.

> Fixes: 5467801f1fcb ("gpio: Restrict usage of GPIO chip irq members before initialization")
> Signed-off-by: Jiawen Wu <jiawenwu@...stnetic.com>
> ---
> v1 -> v2:
> - add compiler barrier
> ---
>  drivers/gpio/gpiolib.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index a7220e04a93e..9ecf93cbd801 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -1792,6 +1792,14 @@ int gpiochip_irqchip_add_domain(struct gpio_chip *gc,
>         gc->to_irq = gpiochip_to_irq;
>         gc->irq.domain = domain;
>
> +       /*
> +        * Using barrier() here to prevent compiler from reordering
> +        * gc->irq.initialized before adding irqdomain.
> +        */
> +       barrier();
> +
> +       gc->irq.initialized = true;
> +
>         return 0;
>  }
>  EXPORT_SYMBOL_GPL(gpiochip_irqchip_add_domain);
> --
> 2.27.0
>


-- 
With Best Regards,
Andy Shevchenko