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;
MIME-Version: 1.0
References: <20200922023151.387447-1-warthog618@gmail.com> <20200922023151.387447-10-warthog618@gmail.com>
 <CAHp75VdyOodxqkJCgmrdmcppyjVkDTyHDB-fqjoKS1g-88-umQ@mail.gmail.com>
 <20200924030732.GB11575@sol> <CAHp75Vd7Bmy5FWSputDCAAwSheH6ugszMyCcu1HOgC7BPVEX-w@mail.gmail.com>
 <20200925122651.GA218809@sol>
In-Reply-To: <20200925122651.GA218809@sol>
From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Fri, 25 Sep 2020 17:48:25 +0300
Message-ID: <CAHp75Vcw0HBwkdCFWpcGLs5MunGmDJBNrCeqmzz-mGDUWGNpog@mail.gmail.com>
Subject: Re: [PATCH v9 09/20] gpiolib: cdev: support edge detection for uAPI v2
To:     Kent Gibson <warthog618@gmail.com>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        Arnd Bergmann <arnd@arndb.de>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Fri, Sep 25, 2020 at 3:26 PM Kent Gibson <warthog618@gmail.com> wrote:
> On Fri, Sep 25, 2020 at 12:35:49PM +0300, Andy Shevchenko wrote:
> > On Thu, Sep 24, 2020 at 6:07 AM Kent Gibson <warthog618@gmail.com> wrote:
> > > On Wed, Sep 23, 2020 at 06:47:28PM +0300, Andy Shevchenko wrote:
> > > > On Tue, Sep 22, 2020 at 5:35 AM Kent Gibson <warthog618@gmail.com> wrote:

...

> > > > > +       if (!line->timestamp_ns) {
> > > > > +               le.timestamp_ns = ktime_get_ns();
> > > > > +               if (lr->num_lines != 1)
> > > > > +                       line->req_seqno = atomic_inc_return(&lr->seqno);
> > > > > +       } else {
> > > > > +               le.timestamp_ns = line->timestamp_ns;
> > > > > > +       }
> > > >
> > > > Ditto.
> > >
> > > Firstly, drawn from lineevent_irq_thread() which is structured this way.
> > >
> > > In this case the comment relates to the condition being true, so
> > > re-ordering the if/else would be confusing - unless the comment were
> > > moved into the corresponding body??
> >
> > Yes.
> >
>
> Does that mean I should re-order and move the comment into the body?
> That would work for me - the normal case is line->timestamp_ns being
> set.

Yes, that's what I meant.

...

> > > From gpiod_to_irq():
> > >
> > >                 /* Zero means NO_IRQ */
> > >                 if (!retirq)
> > >                         return -ENXIO;
> > >
> > > so it can't even return a 0 :-| - we're just being cautious.
> >
> > I would drop = part then.
> >
>
> ok, but you'd better not come after me in a subsequent review for not
> checking the 0 case!

For IRQ?! Maybe if I'll be drunk (quite unlikely).

I really don't like to check IRQ against 0. To me it should be
transparent to the caller. If IRQ == 0 in certain API or entirely in
Linux is considered NO_IRQ, then it should be either correctly handled
(means all following actions on it shouldn't fail, or it shouldn't be
returned in the first place).

-- 
With Best Regards,
Andy Shevchenko