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From: Andy Shevchenko <andy.shevchenko@gmail.com>
Date: Thu, 18 Jan 2024 11:03:44 +0200
Message-ID: <CAHp75Vf4wXLEjmfpz6KQSCB0Jd8LNv6+SU_ikbhR_8PsJHuq-g@mail.gmail.com>
Subject: Re: [PATCH v3 1/3] gpio: vf610: add support to DT 'ngpios' property
To: Hector Palacios <hector.palacios@digi.com>
Cc: linus.walleij@linaro.org, brgl@bgdev.pl, robh+dt@kernel.org, 
	krzysztof.kozlowski+dt@linaro.org, andy@kernel.org, conor+dt@kernel.org, 
	shawnguo@kernel.org, s.hauer@pengutronix.de, kernel@pengutronix.de, 
	festevam@gmail.com, linux-imx@nxp.com, stefan@agner.ch, 
	linux-gpio@vger.kernel.org, devicetree@vger.kernel.org, 
	linux-kernel@vger.kernel.org
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On Thu, Jan 18, 2024 at 10:25=E2=80=AFAM Hector Palacios
<hector.palacios@digi.com> wrote:
> On 1/17/24 21:51, Andy Shevchenko wrote:
> >> Some SoCs, such as i.MX93, don't have all 32 pins available
> >> per port. Allow optional generic 'ngpios' property to be
> >> specified from the device tree and default to
> >> VF610_GPIO_PER_PORT (32) if the property does not exist.

..

> >> +       ret =3D device_property_read_u32(dev, "ngpios", &ngpios);
> >> +       if (ret || ngpios > VF610_GPIO_PER_PORT)
> >> +               gc->ngpio =3D VF610_GPIO_PER_PORT;
> >> +       else
> >> +               gc->ngpio =3D (u16)ngpios;
> >
> > This property is being read by the GPIOLIB core. Why do you need to rep=
eat this?
>
> My apologies; I had not seen this.
> I'll use gpiochip_get_ngpios() on the next iteration.

But still why?
https://elixir.bootlin.com/linux/latest/source/drivers/gpio/gpiolib.c#L867

It's called for every driver.

Maybe it's needed to be refactored to allow fallbacks? Then can the
GPIO MMIO case also be updated?

--=20
With Best Regards,
Andy Shevchenko