linux-kernel - Re: [PATCH 1/3] gpio: tqmx86: really make IRQ optional

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Message-ID: <38b1191ce594d9fefe9e0e98b3fa8ca0a23ee3ea.camel@ew.tq-group.com>
Date:   Wed, 31 Mar 2021 15:36:22 +0200
From:   Matthias Schiffer <matthias.schiffer@...tq-group.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Lee Jones <lee.jones@...aro.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] gpio: tqmx86: really make IRQ optional

On Wed, 2021-03-31 at 15:39 +0300, Andy Shevchenko wrote:
> On Wed, Mar 31, 2021 at 3:37 PM Matthias Schiffer
> <matthias.schiffer@...tq-group.com> wrote:
> > On Wed, 2021-03-31 at 15:29 +0300, Andy Shevchenko wrote:
> > > On Wed, Mar 31, 2021 at 2:37 PM Matthias Schiffer
> > > <matthias.schiffer@...tq-group.com> wrote:
> 
> ...
> 
> > > > -       irq = platform_get_irq(pdev, 0);
> > > > -       if (irq < 0)
> > > > +       irq = platform_get_irq_optional(pdev, 0);
> > > > +       if (irq < 0 && irq != -ENXIO)
> > > >                 return irq;
> > > 
> > > This is a dead code now. I suggest you to do the opposite, i.e.
> > > if (irq < 0)
> > >   irq = 0;
> > 
> > I don't understand which part of the code is dead now. I assume the
> > `return irq` case is still useful for unexpected errors, or things like
> > EPROBE_DEFER? I'm not sure if EPROBE_DEFER is relevant for this driver,
> > but just ignoring the error code completely doesn't seem right to me.
> 
> platform_get_irq() AFAIK won't ever return such a code.
> So, basically your conditional is always false.
> 
> I would like to see the code path which makes my comment wrong.
> 

EPROBE_DEFER appears a few times in platform_get_irq_optional()
(drivers/base/platform.c), but it's possible that this is only relevant
for OF-based platforms and not x86.