linux-kernel - Re: [PATCH] pinctrl: pinconf-generic: check error value EOPNOTSUPP

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Message-ID: <ZhAe9oFz9wLQi4de@smile.fi.intel.com>
Date: Fri, 5 Apr 2024 18:55:34 +0300
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: Sudeep Holla <sudeep.holla@....com>
Cc: Peng Fan <peng.fan@....com>, Linus Walleij <linus.walleij@...aro.org>,
	"Peng Fan (OSS)" <peng.fan@....nxp.com>,
	"brgl@...ev.pl" <brgl@...ev.pl>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"cristian.marussi@....com" <cristian.marussi@....com>
Subject: Re: [PATCH] pinctrl: pinconf-generic: check error value EOPNOTSUPP

On Fri, Apr 05, 2024 at 04:47:19PM +0100, Sudeep Holla wrote:
> On Fri, Apr 05, 2024 at 06:38:04PM +0300, Andy Shevchenko wrote:
> > On Fri, Apr 05, 2024 at 02:13:28AM +0000, Peng Fan wrote:
> > > > On Thu, Apr 04, 2024 at 01:44:50PM +0200, Linus Walleij wrote:
> > > > > On Mon, Apr 1, 2024 at 4:02 PM Peng Fan (OSS) <peng.fan@....nxp.com>
> > > > wrote:

..

> > > > This check opens a Pandora box.
> > > >
> > > > FWIW, it just like dozen or so drivers that needs to be fixed, I prefer to have
> > > > them being moved to ENOTSUPP, rather this patch.
> > >
> > > I see many patches convert to use EOPNOTSUPP by checking git log.
> >
> > How is that related? You mean for GPIO/pin control drivers?
> >
> > > And checkpatch.pl reports warning for using ENOTSUPP.
> >
> > checkpatch has false-positives, this is just one of them.
> 
> Fair enough.
> 
> > > BTW: is there any issue if using EOPNOTSUPP here?
> >
> > Yes. we don't want to be inconsistent. Using both in one subsystem is asking
> > for troubles. If you want EOPNOTSUPP, please convert *all* users and drop
> > ENOTSUPP completely (series out of ~100+ patches I believe :-), which probably
> > will be not welcome).
> 
> Well, I don't agree with that 100% now since this is GPIO/pinmux sub-system
> practice only.

	git grep -lw ENOTSUPP

utterly disagrees with you.

> What if we change the source/root error cause(SCMI) in this
> case and keep GPIO/pinmux happy today but tomorrow when this needs to be
> used in some other subsystem which uses EOPNOTSUPP by default/consistently.

This is different case. For that we may shadow error codes with explicit
comments.

> Now how do we address that then, hence I mentioned I am not 100% in agreement
> now while I was before knowing that this is GPIO/pinmux strategy.
> 
> I don't know how to proceed now 🙁.

KISS principle? There are only 10+ drivers to fix (I showed a rough list)
to use ENOTSUPP instead of 100s+ otherwise.

-- 
With Best Regards,
Andy Shevchenko