Re: [PATCH regression fix v2] gpiolib: acpi: Make set-debounce-timeout failures non fatal

[Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>]

On Mon, Aug 16, 2021 at 12:41:19PM +0200, Hans de Goede wrote:
> Commit 8dcb7a15a585 ("gpiolib: acpi: Take into account debounce settings")
> made the gpiolib-acpi code call gpio_set_debounce_timeout() when requesting
> GPIOs.
> 
> This in itself is fine, but it also made gpio_set_debounce_timeout()
> errors fatal, causing the requesting of the GPIO to fail. This is causing
> regressions. E.g. on a HP ElitePad 1000 G2 various _AEI specified GPIO
> ACPI event sources specify a debouncy timeout of 20 ms, but the
> pinctrl-baytrail.c only supports certain fixed values, the closest
> ones being 12 or 24 ms and pinctrl-baytrail.c responds with -EINVAL
> when specified a value which is not one of the fixed values.
> 
> This is causing the acpi_request_own_gpiod() call to fail for 3
> ACPI event sources on the HP ElitePad 1000 G2, which in turn is causing
> e.g. the battery charging vs discharging status to never get updated,
> even though a charger has been plugged-in or unplugged.
> 
> Make gpio_set_debounce_timeout() errors non fatal, warning about the
> failure instead, to fix this regression.
> 
> Note we should probably also fix various pinctrl drivers to just
> pick the first bigger discrete value rather then returning -EINVAL but
> this will need to be done on a per driver basis, where as this fix
> at least gets us back to where things were before and thus restores
> functionality on devices where this was lost due to
> gpio_set_debounce_timeout() errors.

Yes, I also think that we need to choose upper debounce instead of rejecting
the settings. And yes, I agree that for now it's not suitable as a fix.

That said,
Acked-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

> Fixes: 8dcb7a15a585 ("gpiolib: acpi: Take into account debounce settings")
> Depends-on: 2e2b496cebef ("gpiolib: acpi: Extract acpi_request_own_gpiod() helper")
> Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> ---
> Changes in v2:
> -Fix typo in commit msg
> -Add Mika's Reviewed-by
> -Add Depends-on tag
> ---
>  drivers/gpio/gpiolib-acpi.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
> index 411525ac4cc4..47712b6903b5 100644
> --- a/drivers/gpio/gpiolib-acpi.c
> +++ b/drivers/gpio/gpiolib-acpi.c
> @@ -313,9 +313,11 @@ static struct gpio_desc *acpi_request_own_gpiod(struct gpio_chip *chip,
>  
>  	ret = gpio_set_debounce_timeout(desc, agpio->debounce_timeout);
>  	if (ret)
> -		gpiochip_free_own_desc(desc);
> +		dev_warn(chip->parent,
> +			 "Failed to set debounce-timeout for pin 0x%04X, err %d\n",
> +			 pin, ret);
>  
> -	return ret ? ERR_PTR(ret) : desc;
> +	return desc;
>  }
>  
>  static bool acpi_gpio_in_ignore_list(const char *controller_in, int pin_in)
> -- 
> 2.31.1
> 

-- 
With Best Regards,
Andy Shevchenko