Re: [PATCH] gpiolib: acpi: Do not set the IRQ type if the IRQ is already in use

[Andy Shevchenko <andriy.shevchenko@intel.com>]

On Mon, Nov 22, 2021 at 11:04:16PM +0100, Hans de Goede wrote:
> If the IRQ is already in use, then acpi_dev_gpio_irq_get_by() really
> should not change the type underneath the current owner.
> 
> I specifically hit an issue with this an a Chuwi Hi8 Super (CWI509) Bay
> Trail tablet, when the Boot OS selection in the BIOS is set to Android.
> In this case _STA for a MAX17047 ACPI I2C device wrongly returns 0xf and
> the _CRS resources for this device include a GpioInt pointing to a GPIO
> already in use by an _AEI handler, with a different type then specified
> in the _CRS for the MAX17047 device. Leading to the acpi_dev_gpio_irq_get()
> call done by the i2c-core-acpi.c code changing the type breaking the
> _AEI handler.
> 
> Now this clearly is a bug in the DSDT of this tablet (in Android mode),
> but in general calling irq_set_irq_type() on an IRQ which already is
> in use seems like a bad idea.

I'm fine with the change, one comment below, though.

> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
>  drivers/gpio/gpiolib-acpi.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
> index 985e8589c58b..24cd86bf2c4c 100644
> --- a/drivers/gpio/gpiolib-acpi.c
> +++ b/drivers/gpio/gpiolib-acpi.c
> @@ -1056,8 +1056,12 @@ int acpi_dev_gpio_irq_get_by(struct acpi_device *adev, const char *name, int ind
>  			irq_flags = acpi_dev_get_irq_type(info.triggering,
>  							  info.polarity);
>  
> -			/* Set type if specified and different than the current one */
> -			if (irq_flags != IRQ_TYPE_NONE &&
> +			/*
> +			 * If the IRQ is not already in use then set type
> +			 * if specified and different than the current one.
> +			 */
> +			if (can_request_irq(irq, irq_flags) &&
> +			    irq_flags != IRQ_TYPE_NONE &&
>  			    irq_flags != irq_get_trigger_type(irq))
>  				irq_set_irq_type(irq, irq_flags);

What about issuing a debug (?) message

			if (can_request_irq(irq, irq_flags) {
				if (irq_flags != IRQ_TYPE_NONE &&
				    irq_flags != irq_get_trigger_type(irq))
					irq_set_irq_type(irq, irq_flags);
			} else {
				dev_dbg(..., FW_BUG "IRQ %d already in use\n", irq);
			}

?

-- 
With Best Regards,
Andy Shevchenko