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

On Wed, Jun 7, 2023 at 11:20=E2=80=AFAM Jiawen Wu <jiawenwu@trustnetic.com>=
 wrote:
>
> In case of gpio-regmap, IRQ chip is added by regmap-irq and associated wi=
th
> GPIO chip by gpiochip_irqchip_add_domain(). The initialization flag was n=
ot
> added in gpiochip_irqchip_add_domain(), causing gpiochip_to_irq() to retu=
rn
> -EPROBE_DEFER.

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

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

> Fixes: 5467801f1fcb ("gpio: Restrict usage of GPIO chip irq members befor=
e initialization")
> Signed-off-by: Jiawen Wu <jiawenwu@trustnetic.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 =3D gpiochip_to_irq;
>         gc->irq.domain =3D domain;
>
> +       /*
> +        * Using barrier() here to prevent compiler from reordering
> +        * gc->irq.initialized before adding irqdomain.
> +        */
> +       barrier();
> +
> +       gc->irq.initialized =3D true;
> +
>         return 0;
>  }
>  EXPORT_SYMBOL_GPL(gpiochip_irqchip_add_domain);
> --
> 2.27.0
>


--=20
With Best Regards,
Andy Shevchenko