Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Message-ID: <bf12f668db2f0dce7dfc09351780e295da30714c.camel@fi.rohmeurope.com>
Subject: Re: [PATCH 2/2] gpiolib: Allow drivers to return EOPNOTSUPP from
 config
From:   Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Reply-To: matti.vaittinen@fi.rohmeurope.com
To:     Andy Shevchenko <andy.shevchenko@gmail.com>,
        Joe Perches <joe@perches.com>
Cc:     Linus Walleij <linus.walleij@linaro.org>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>,
        Stephen Boyd <sboyd@codeaurora.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
In-Reply-To: <CAHp75VdXa2bkJ+ej+HNYstLeK4TF+L5H3wTgm0CgJ9hYQeU+ZQ@mail.gmail.com>
References: <cover.1617017060.git.matti.vaittinen@fi.rohmeurope.com>
         <d2c8b7f9a3b420c2764f645da531a57db16905f3.1617017060.git.matti.vaittinen@fi.rohmeurope.com>
         <CAHp75VdXa2bkJ+ej+HNYstLeK4TF+L5H3wTgm0CgJ9hYQeU+ZQ@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
MIME-Version: 1.0
Date:   Mon, 29 Mar 2021 15:20:07 +0300
User-Agent: Evolution 3.34.4 (3.34.4-1.fc31) 
Content-Transfer-Encoding: 7bit
Precedence: bulk

On Mon, 2021-03-29 at 14:59 +0300, Andy Shevchenko wrote:
> On Mon, Mar 29, 2021 at 2:43 PM Matti Vaittinen
> <matti.vaittinen@fi.rohmeurope.com> wrote:
> > The checkpacth instructs to switch from ENOSUPP to EOPNOTSUPP.
> > > WARNING: ENOTSUPP is not a SUSV4 error code, prefer EOPNOTSUPP
> > 
> > Make the gpiolib allow drivers to return both so driver developers
> > can avoid one of the checkpatch complaints.
> 
> Internally we are fine to use the ENOTSUPP.
> Checkpatch false positives there.

I agree. OTOH, the checkpatch check makes sense to user-visible stuff.
Yet, the checkpatch has hard time guessing what is user-visible - so it
probably is easiest to nag about all ENOTSUPP uses as it does now.

> I doubt we need this change. Rather checkpatch should rephrase this
> to
> point out that this is only applicable to _user-visible_ error path.
> Cc'ed Joe.

Yes, thanks for pulling Joe in.

Anyways, no matter what the warning says, all false positives are
annoying. I don't see why we should stay with ENOTSUPP in gpiolib?
(other than the burden of changing it).

But I have no strong opinion on this. All options I see have downsides.

Accepting both ENOTSUPP and EOPNOTSUPP is the easy way to avoid
allowing checkpatch warnings - but I admit it isn't stylish. 

Converting all ENOTSUPP cases inside gpiolib to EOPNOTSUPP is teodious
although end result might be nicer.

Leaving it as is gives annoying false-positives to driver developers.

My personal preference was this patch - others can have other view like
Andy does. I'll leave this to community/maintainers to evaluate :)

Best Regards
	Matti Vaittinen