linux-kernel - Re: [PATCH V2 3/3] gpio: modepin: Add driver support for modepin GPIO controller

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Date:   Wed, 11 Aug 2021 14:59:48 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Piyush Mehta <piyush.mehta@...inx.com>
Cc:     Arnd Bergmann <arnd@...db.de>, Zou Wei <zou_wei@...wei.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Michal Simek <michal.simek@...inx.com>, wendy.liang@...inx.com,
        Nobuhiro Iwamatsu <iwamatsu@...auri.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Rob Herring <robh+dt@...nel.org>, rajan.vaja@...inx.com,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, git <git@...inx.com>,
        Srinivas Goud <sgoud@...inx.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V2 3/3] gpio: modepin: Add driver support for modepin GPIO controller

Hi Piyush,

thanks for your patch!

Can you explain one thing to me: since this is now a GPIO driver
that means "General Purpos Input/Output", then these bits are
accessed like this:

On Thu, Aug 5, 2021 at 7:43 PM Piyush Mehta <piyush.mehta@...inx.com> wrote:

> +       ret = zynqmp_pm_bootmode_read(&bootpin_val);

This does not look very general purpose. These seem to be all about
boot mode, right?

So can you explain why this should be a GPIO driver at all?

I understand it is sometimes convenient to describe stuff as GPIO even
if it is not (for example to get a convenient userspace interface) but
as maintainers
we really need to make sure that the subsystem is not being abused
for things not GPIO.

Yours,
Linus Walleij