Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20221108092840.14945-1-JJLIU0@nuvoton.com> <20221108092840.14945-4-JJLIU0@nuvoton.com>
 <CACRpkdb+Bkwa8yCKGtRcsJ6KnJh+RUuz_gOrQV63pcYQLaHCaw@mail.gmail.com> <CAKUZ0+GCf_Zv=VhnY5Z=yYAfR1=_ha98BVVxRGVy8ui6so_Yrg@mail.gmail.com>
In-Reply-To: <CAKUZ0+GCf_Zv=VhnY5Z=yYAfR1=_ha98BVVxRGVy8ui6so_Yrg@mail.gmail.com>
From:   Linus Walleij <linus.walleij@linaro.org>
Date:   Fri, 11 Nov 2022 15:20:02 +0100
Message-ID: <CACRpkdYW0P8gqtGdiRX_frP32WF2W=NVg1JTu1fVMBXxEL0-WA@mail.gmail.com>
Subject: Re: [PATCH v2 3/3] dt-bindings: gpio: Add Nuvoton NPCM750 serial I/O
 expansion interface(SGPIO)
To:     Jim Liu <jim.t90615@gmail.com>
Cc:     JJLIU0@nuvoton.com, KWLIU@nuvoton.com, brgl@bgdev.pl,
        robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, openbmc@lists.ozlabs.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Fri, Nov 11, 2022 at 10:30 AM Jim Liu <jim.t90615@gmail.com> wrote:

> -D_out:
> the output data is the serial data needed to connect to hc595 and the
> data will output to hc595 parallel pins.
> you can use dts nout_gpios to create the number of pins.
>
> -D_in
> this pin need to connect to hc165 and get the serial data from hc165.
> you can use dts nin_gpios to create the number of pins.

In the example it seems you enable d_out and d_in for *all* 64
pins, correct? So they are all either input or output.

That in effect turns them into GPIOs, so I don't see the problem
with simply always doing this?

Just that things are configurable doesn't mean we always need
to provide means to configure them.

If you have a use case where the user wants to control this, then
that is another thing. Otherwise just make all pins input and output
and wait for a usecase that needs more control, maybe it will
never appear.

Yours,
Linus Walleij