linux-kernel - Re: [PATCH][GPIO] Add IRQ edge setter to gpiolib

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Message-ID: <CACRpkdb+txD9hfhs7pfnzmDuU59VXEdzJc86z=tdy2yqYBCqOg@mail.gmail.com>
Date:	Tue, 9 Oct 2012 14:00:34 +0200
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Drasko DRASKOVIC <drasko.draskovic@...il.com>,
	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	Grant Likely <grant.likely@...retlab.ca>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH][GPIO] Add IRQ edge setter to gpiolib

On Fri, Oct 5, 2012 at 3:16 PM, Drasko DRASKOVIC
<drasko.draskovic@...il.com> wrote:
> [Me]
>> If I understand correctly the below more or less exports
>> struct irq_chip to userspace,
>> trying to hide it by instead exposing a property of the
>> containing struct gpio_chip and it worries me.
>
> No, it should not.

You are exporting all of the defines from irq.h,
IRQ_TYPE_NONE, IRQ_TYPE_EDGE_FALLING, etc
to userspace. These are defined in <linux/irq.h> and that file
has this comment on top:

/*
 * Please do not include this file in generic code.  There is currently
 * no requirement for any architecture to implement anything held
 * within this file.
 *
 * Thanks. --rmk
 */

And that comment is even only about generic *KERNEL* code,
userspace is way, way more than that.

> It operates only on already exported gpiochip
> (similar to gpio_export_link()).
> It just helps exported GPIO be configured in "interrupt" and not in
> "normal" mode.

So can you explain exactly why userspace want to configure
GPIO pins in interrupt mode, when there is no way whatsoever
for userspace to handle these IRQs?

Yours,
Linus Walleij
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