linux-kernel - Re: [PATCH v6 2/2] pinctrl: amd: Fix wakeups when IRQ is shared with SCI

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Date:   Sun, 31 Oct 2021 15:15:12 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Mario Limonciello <mario.limonciello@....com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Basavaraj Natikar <Basavaraj.Natikar@....com>,
        Shyam Sundar S K <Shyam-sundar.S-k@....com>,
        "open list:PIN CONTROL SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Nehal Shah <Nehal-bakulchandra.Shah@....com>,
        stable@...nel.org, Joerie de Gram <j.de.gram@...il.com>
Subject: Re: [PATCH v6 2/2] pinctrl: amd: Fix wakeups when IRQ is shared with SCI

On Fri, Oct 29, 2021 at 11:42 PM Mario Limonciello
<mario.limonciello@....com> wrote:
>
> On some Lenovo AMD Gen2 platforms the IRQ for the SCI and pinctrl drivers
> are shared.  Due to how the s2idle loop handling works, this case needs
> an extra explicit check whether the interrupt was caused by SCI or by
> the GPIO controller.
>
> To fix this rework the existing IRQ handler function to function as a
> checker and an IRQ handler depending on the calling arguments.
>
> Cc: stable@...nel.org
> BugLink: https://gitlab.freedesktop.org/drm/amd/-/issues/1738
> Reported-by: Joerie de Gram <j.de.gram@...il.com>
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> Acked-by: Basavaraj Natikar <Basavaraj.Natikar@....com>

...

> +static bool _amd_gpio_irq_handler(int irq, void *dev_id)

I know Linus does not like leading _* in the function names, what
about 'do_' instead?

...

> +                       /* called from resume context on a shared IRQ, just
> +                        * checking wake source.
> +                        */

Is this comment aligned with the style used elsewhere in the driver code?

...

> +                               dev_dbg(&gpio_dev->pdev->dev,
> +                                       "Waking due to GPIO %ld: 0x%x",
> +                                       (long)(regs + i - ((u32 __iomem *)gpio_dev->base)), regval);

Oy vey, these castings are ugly. The rule of thumb is that if one does
such a thing for printf() it means something is really wrong (in 99%
of the cases).

AFAICS you may simply use 'irqnr + i' as the other message does.

...

>         platform_set_drvdata(pdev, gpio_dev);
> +       acpi_register_wakeup_handler(gpio_dev->irq, amd_gpio_check_wake, gpio_dev);
>
>         dev_dbg(&pdev->dev, "amd gpio driver loaded\n");
>         return ret;
> @@ -1021,6 +1045,7 @@ static int amd_gpio_remove(struct platform_device *pdev)
>         gpio_dev = platform_get_drvdata(pdev);
>
>         gpiochip_remove(&gpio_dev->gc);
> +       acpi_unregister_wakeup_handler(amd_gpio_check_wake, gpio_dev);

Thinking about making this in the generic GPIO library code, but this
is out of scope of the patch...

-- 
With Best Regards,
Andy Shevchenko