Re: [PATCH] gpiolib: acpi: Program debounce when finding GPIO

[Mika Westerberg <mika.westerberg@linux.intel.com>]

Hi,

On Sun, Aug 17, 2025 at 08:52:07PM -0500, Mario Limonciello (AMD) wrote:
> When soc-button-array looks up the GPIO to use it calls acpi_find_gpio()
> which will parse _CRS.
> 
> acpi_find_gpio.cold (drivers/gpio/gpiolib-acpi-core.c:953)
> gpiod_find_and_request (drivers/gpio/gpiolib.c:4598 drivers/gpio/gpiolib.c:4625)
> gpiod_get_index (drivers/gpio/gpiolib.c:4877)
> 
> The GPIO is setup basically, but the debounce information is discarded.
> The platform will assert what debounce should be in _CRS, so program it
> at the time it's available.

The spec says for GpioInt():

  DebounceTimeout is an optional argument specifying the debounce wait
  time, in hundredths of milliseconds. The bit field name _DBT is
  automatically created to refer to this portion of the resource
  descriptor.

I was not sure but wanted to check that if it is left out, does ACPICA fill
it with 0? If yes (I would expect so) then this is fine.

> Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
> ---
> v4:

You missed "v4" in the $subject.

>  * Just add a direct call instead
>  * drop tag
>  * update commit message
> ---
>  drivers/gpio/gpiolib-acpi-core.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/gpio/gpiolib-acpi-core.c b/drivers/gpio/gpiolib-acpi-core.c
> index 12b24a717e43f..6388e8e363dee 100644
> --- a/drivers/gpio/gpiolib-acpi-core.c
> +++ b/drivers/gpio/gpiolib-acpi-core.c
> @@ -944,6 +944,7 @@ struct gpio_desc *acpi_find_gpio(struct fwnode_handle *fwnode,
>  	bool can_fallback = acpi_can_fallback_to_crs(adev, con_id);
>  	struct acpi_gpio_info info;
>  	struct gpio_desc *desc;
> +	int ret;
>  
>  	desc = __acpi_find_gpio(fwnode, con_id, idx, can_fallback, &info);
>  	if (IS_ERR(desc))
> @@ -957,6 +958,11 @@ struct gpio_desc *acpi_find_gpio(struct fwnode_handle *fwnode,
>  
>  	acpi_gpio_update_gpiod_flags(dflags, &info);
>  	acpi_gpio_update_gpiod_lookup_flags(lookupflags, &info);
> +	/* ACPI uses hundredths of milliseconds units */
> +	ret = gpio_set_debounce_timeout(desc, info.debounce * 10);
> +	if (ret)
> +		return ERR_PTR(ret);
> +
>  	return desc;
>  }
>  
> -- 
> 2.43.0