linux-kernel - Re: [PATCH 5/6] gpiolib: cdev: consolidate edge detector configuration flags

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Message-ID: <20220713102459.GA113115@sol>
Date:   Wed, 13 Jul 2022 18:24:59 +0800
From:   Kent Gibson <warthog618@...il.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Linus Walleij <linus.walleij@...aro.org>,
        Dipen Patel <dipenp@...dia.com>
Subject: Re: [PATCH 5/6] gpiolib: cdev: consolidate edge detector
 configuration flags

On Wed, Jul 13, 2022 at 12:07:29PM +0200, Andy Shevchenko wrote:
> On Wed, Jul 13, 2022 at 3:39 AM Kent Gibson <warthog618@...il.com> wrote:
> >
> > Combine the polarity_change flag, struct line eflags, and hte enable
> > flag into a single flag variable.
> >
> > The combination of these flags describes the configuration state
> > of the edge detector, so formalize and clarify that by combining
> > them into a single variable, edflags, in struct line.
> >
> > The edflags is a subset of the GPIO_V2_LINE_FLAGsb relevant to
> > the edge detector, and is also a superset of the eflags it replaces.
> > The eflags name is still used to describe the subset of edflags
> > corresponding to the rising/falling edge flags where edflags is
> > masked down to that subset.
> >
> > This consolidation reduces the number of variables being passed,
> > simplifies state comparisons, and provides a more extensible
> > foundation should additional edge sources be integrated in the
> > future.
> 
> I believe that you have checked this from a locking perspective, so we
> won't have worse lock contamination, if any.
> 

Yeah, they are used in the same way as the old eflags, so there is no
change in that regard.

> ...
> 
> >         struct linereq *lr;
> >         struct gpio_v2_line_event le;
> >         int level;
> > -       u64 eflags;
> > +       u64 edflags;
> 
> I would at the same time move it up before `int level;`.
> 

Ok.  What is the general rule you want applied, cos I'm not seeing it.

Cheers,
Kent.

> ...
> 
> > +       int level = -1, diff_seqno;
> > +       u64 eflags, edflags = READ_ONCE(line->edflags);
> 
> Ditto.
> 
> ...
> 
> >         u32 debounce_period_us;
> >         unsigned long irqflags = 0;
> >         int irq, ret;
> > +       u64 eflags;
> 
> Ditto for similarity.
> 
> -- 
> With Best Regards,
> Andy Shevchenko