Re: [PATCH v3] gpiolib: acpi: Program debounce when finding GPIO

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

On Mon, Aug 11, 2025 at 11:43:56AM -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.
> 
> As this is considered non fatal if it fails, introduce a helper for
> programming debounce and show a warning when failing to program.

I think I already commented on this previously. Let me do that below anyway.

...


> +static void acpi_set_debounce_timeout(struct gpio_desc *desc, unsigned int timeout)
> +{
> +	int ret;
> +
> +	/* ACPI uses hundredths of milliseconds units */
> +	ret = gpio_set_debounce_timeout(desc, timeout * 10);
> +	if (ret)
> +		dev_warn(&desc->gdev->dev,
> +			 "Failed to set debounce-timeout: %d\n", ret);
> +}

I would make it still return the code to the caller. See below why.


...

> -			/* ACPI uses hundredths of milliseconds units */
> -			ret = gpio_set_debounce_timeout(desc, info.debounce * 10);
> -			if (ret)
> -				return ret;
> +			acpi_set_debounce_timeout(desc, info.debounce);

The commit message fails to explain why we do relax the condition here. This is
about GpioInt() resource and so far I haven't heard about misused debounce
values there. If we drop the fatality, it has to be a separate patch explaining
why. But only if we have practical use cases. AS long as there no failed
platforms, I can't agree on this piece of change.

-- 
With Best Regards,
Andy Shevchenko