Re: [PATCH v2] pinctrl: bcm63268: add gpio function

[Álvaro Fernández Rojas <noltari@xxxxxxxxx>]

El sáb, 4 ene 2025 a las 16:44, Álvaro Fernández Rojas
(<noltari@xxxxxxxxx>) escribió:
>
> El vie, 3 ene 2025 a las 4:04, Kyle Hendry (<kylehendrydev@xxxxxxxxx>) escribió:
> >
> > On 2024-12-30 08:42, Jonas Gorski wrote:
> > > Hi,
> > >
> > > On Tue, Dec 24, 2024 at 11:41 AM Álvaro Fernández Rojas
> > > <noltari@xxxxxxxxx> wrote:
> > >> From: Kyle Hendry <kylehendrydev@xxxxxxxxx>
> > >>
> > >> There is no guarantee that the bootloader will leave the pin configuration
> > >> in a known default state, so pinctrl needs to be explicitly set in some
> > >> cases. This patch adds a gpio function for drivers that need it, i.e.
> > >> gpio-leds.
> > >>
> > >> Signed-off-by: Kyle Hendry <kylehendrydev@xxxxxxxxx>
> > >> Signed-off-by: Álvaro Fernández Rojas <noltari@xxxxxxxxx>
> > >
> > > bcm63268-pinctrl implements pinmux_ops::gpio_request_enable(), which
> > > should automatically set any requested GPIO pin to the GPIO function,
> > > so explicitly requesting the gpio function for a pin should not be
> > > needed. Is this not enough?
> > >
> > > Best Regards,
> > > Jonas
> > >
> > >
> > I assumed that as well, but nothing I tried worked with gpio-leds.
> > gpiochip_generic_request() does call gpio_request_enable(), but gpio-leds
> > uses devm_fwnode_gpiod_get() which looks like a different code path. The
> > only place it seems to be configuring the gpio is in create_gpio_led()
> > where it needs a pinctl node in the device tree. That's just my reading
> > of the code, though. I haven't set up a ftrace to verify it.
> >
> > Best Regards,
> > Kyle
>
> As Kyle pointed out it's not enough and gpio_request_enable() doesn't
> get called from gpio-leds.
> I will try to investigate this and report back.
>
> Best regards,
> Álvaro.

I've performed some tests and so far I haven't been able to get
bcm63268_gpio_request_enable() called.

Even exporting a gpio from userspace doesn't trigger that function,
which seems strange because in that case we won't have a "gpio"
function on the pinctrl for that gpio, even with this patch...

Best regards,
Álvaro.