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

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 8/16/21 2:15 PM, Andy Shevchenko wrote:
> 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@linux.intel.com>

Thank you.

FYI, I've prepared a patch to choose the upper debounce time for
pintctrl-baytrail . I'll test it when I'm back home tonight and
then submit it upstream.

Regards,

Hans




> 
>> 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@linux.intel.com>
>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
>> ---
>> 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
>>
>