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

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

On Mon, Aug 18, 2025 at 01:03:48PM -0500, Mario Limonciello wrote:
> On 8/17/25 11:55 PM, Mika Westerberg wrote:
> > 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.
> 
> Yeah AFAICT you're right.  The ACPI resource is zero'ed out, so if the field
> was empty it should default to zero.

Okay good.

Then from my perspective,

Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>

> > 
> > > Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
> > > ---
> > > v4:
> > 
> > You missed "v4" in the $subject.
> 
> Whoops, thanks.  If there ends up being a reason to spin I'll send the next
> one as a v5.
> 
> > 
> > >   * 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