linux-kernel - Re: [PATCH v3] gpio-mlxbf2: only get IRQ for device instances 0 and 3

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Message-ID: <CAMRc=Mfg42wvT9qdYrhvFq_wdvThmWpbvvo-p9bHSsyK0pn+bw@mail.gmail.com>
Date: Tue, 22 Jul 2025 16:52:02 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: David Thompson <davthompson@...dia.com>, 
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, 
	Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc: linus.walleij@...aro.org, davem@...emloft.net, asmaa@...dia.com, 
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, 
	stable@...r.kernel.org, Shravan Kumar Ramani <shravankr@...dia.com>
Subject: Re: [PATCH v3] gpio-mlxbf2: only get IRQ for device instances 0 and 3

On Mon, Jul 21, 2025 at 6:22 PM David Thompson <davthompson@...dia.com> wrote:
>
> The gpio-mlxbf2 driver interfaces with four GPIO controllers,
> device instances 0-3. There are two IRQ resources shared between
> the four controllers, and they are found in the ACPI table for
> device instances 0 and 3.  The driver should not attempt to get
> an IRQ resource when probing device instance 1 or 2, otherwise
> the following error is logged:
>   mlxbf2_gpio MLNXBF22:01: error -ENXIO: IRQ index 0 not found
>
> Fixes: 2b725265cb08 ("gpio: mlxbf2: Introduce IRQ support")
> Cc: stable@...r.kernel.org
> Signed-off-by: David Thompson <davthompson@...dia.com>
> Reviewed-by: Shravan Kumar Ramani <shravankr@...dia.com>
> ---
> v3: added version history
> v2: added tag "Cc: stable@...r.kernel.org"
>
>  drivers/gpio/gpio-mlxbf2.c | 56 ++++++++++++++++++++++++--------------
>  1 file changed, 36 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/gpio/gpio-mlxbf2.c b/drivers/gpio/gpio-mlxbf2.c
> index 6f3dda6b635f..fc56ac81e344 100644
> --- a/drivers/gpio/gpio-mlxbf2.c
> +++ b/drivers/gpio/gpio-mlxbf2.c
> @@ -353,7 +353,9 @@ mlxbf2_gpio_probe(struct platform_device *pdev)
>         struct gpio_chip *gc;
>         unsigned int npins;
>         const char *name;
> +       char *colon_ptr;
>         int ret, irq;
> +       long num;
>
>         name = dev_name(dev);
>
> @@ -397,26 +399,40 @@ mlxbf2_gpio_probe(struct platform_device *pdev)
>         gc->ngpio = npins;
>         gc->owner = THIS_MODULE;
>
> -       irq = platform_get_irq(pdev, 0);
> -       if (irq >= 0) {
> -               girq = &gs->gc.irq;
> -               gpio_irq_chip_set_chip(girq, &mlxbf2_gpio_irq_chip);
> -               girq->handler = handle_simple_irq;
> -               girq->default_type = IRQ_TYPE_NONE;
> -               /* This will let us handle the parent IRQ in the driver */
> -               girq->num_parents = 0;
> -               girq->parents = NULL;
> -               girq->parent_handler = NULL;
> -
> -               /*
> -                * Directly request the irq here instead of passing
> -                * a flow-handler because the irq is shared.
> -                */
> -               ret = devm_request_irq(dev, irq, mlxbf2_gpio_irq_handler,
> -                                      IRQF_SHARED, name, gs);
> -               if (ret) {
> -                       dev_err(dev, "failed to request IRQ");
> -                       return ret;
> +       colon_ptr = strchr(dev_name(dev), ':');
> +       if (!colon_ptr) {
> +               dev_err(dev, "invalid device name format\n");
> +               return -EINVAL;
> +       }
> +
> +       ret = kstrtol(++colon_ptr, 16, &num);
> +       if (ret) {
> +               dev_err(dev, "invalid device instance\n");
> +               return ret;
> +       }
> +

That is *really* fragile. Andy, Mika: does this look remotely correct
to you? I don't know much about ACPI systems.

Bart

> +       if (!num || num == 3) {
> +               irq = platform_get_irq(pdev, 0);
> +               if (irq >= 0) {
> +                       girq = &gs->gc.irq;
> +                       gpio_irq_chip_set_chip(girq, &mlxbf2_gpio_irq_chip);
> +                       girq->handler = handle_simple_irq;
> +                       girq->default_type = IRQ_TYPE_NONE;
> +                       /* This will let us handle the parent IRQ in the driver */
> +                       girq->num_parents = 0;
> +                       girq->parents = NULL;
> +                       girq->parent_handler = NULL;
> +
> +                       /*
> +                        * Directly request the irq here instead of passing
> +                        * a flow-handler because the irq is shared.
> +                        */
> +                       ret = devm_request_irq(dev, irq, mlxbf2_gpio_irq_handler,
> +                                              IRQF_SHARED, name, gs);
> +                       if (ret) {
> +                               dev_err(dev, "failed to request IRQ");
> +                               return ret;
> +                       }
>                 }
>         }
>
> --
> 2.30.1
>