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From: Linus Walleij <linus.walleij@linaro.org>
Date: Fri, 3 May 2024 10:25:08 +0200
Message-ID: <CACRpkda4v6Nu8V3MVamDpfs4qnc89e8Vd8fSyaNsqJQ40GQqZg@mail.gmail.com>
Subject: Re: [PATCH 2/3] gpio: of: support gpio-ranges for multiple gpiochip devices
To: Doug Berger <opendmb@gmail.com>
Cc: Bartosz Golaszewski <brgl@bgdev.pl>, Phil Elwell <phil@raspberrypi.com>, Rob Herring <robh@kernel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Conor Dooley <conor+dt@kernel.org>, 
	Florian Fainelli <florian.fainelli@broadcom.com>, bcm-kernel-feedback-list@broadcom.com, 
	linux-gpio@vger.kernel.org, devicetree@vger.kernel.org, 
	linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
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Hi Dough,

thanks for your patch!

I'm a bit confused here:

On Wed, Apr 24, 2024 at 8:51=E2=80=AFPM Doug Berger <opendmb@gmail.com> wro=
te:


> +               /* Ignore ranges outside of this GPIO chip */
> +               if (pinspec.args[0] >=3D (chip->offset + chip->ngpio))
> +                       continue;
> +               if (pinspec.args[0] + pinspec.args[2] <=3D chip->offset)
> +                       continue;

Here pinspec.args[0] and [2] comes directly from the device tree.

The documentation in Documentation/devicetree/bindings/gpio/gpio.txt
says:

> 2.2) Ordinary (numerical) GPIO ranges
> -------------------------------------
>
> It is useful to represent which GPIOs correspond to which pins on which p=
in
> controllers. The gpio-ranges property described below represents this wit=
h
> a discrete set of ranges mapping pins from the pin controller local numbe=
r space
> to pins in the GPIO controller local number space.
>
> The format is: <[pin controller phandle], [GPIO controller offset],
>                 [pin controller offset], [number of pins]>;
>
> The GPIO controller offset pertains to the GPIO controller node containin=
g the
> range definition.

So I do not understand how pinspec[0] and [2] can ever be compared
to something involving chip->offset which is a Linux-specific offset.

It rather looks like you are trying to accomodate the Linux numberspace
in the ranges, which it was explicitly designed to avoid.

I just don't get it.

So NACK until I understand what is going on here.

Yours,
Linus Walleij