linux-kernel - Re: [PATCH v2] gpio: interrupt consistency check for OF GPIO IRQs

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Date:	Fri, 23 Aug 2013 20:38:04 +0200
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Stephen Warren <swarren@...dotorg.org>
Cc:	Tomasz Figa <tomasz.figa@...il.com>,
	Lars Poeschel <larsi@....tu-dresden.de>,
	Lars Poeschel <poeschel@...onage.de>,
	Grant Likely <grant.likely@...aro.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ian.campbell@...rix.com>,
	Kumar Gala <galak@...eaurora.org>,
	Pawel Moll <pawel.moll@....com>,
	Javier Martinez Canillas <javier.martinez@...labora.co.uk>,
	Enric Balletbo i Serra <eballetbo@...il.com>,
	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	Kevin Hilman <khilman@...aro.org>,
	Balaji T K <balajitk@...com>,
	Tony Lindgren <tony@...mide.com>,
	Jon Hunter <jgchunter@...il.com>
Subject: Re: [PATCH v2] gpio: interrupt consistency check for OF GPIO IRQs

On Thu, Aug 22, 2013 at 10:53 PM, Stephen Warren <swarren@...dotorg.org> wrote:
> On 08/21/2013 05:27 PM, Linus Walleij wrote:
>> On Thu, Aug 22, 2013 at 1:10 AM, Stephen Warren <swarren@...dotorg.org> wrote:
>>>> On Wednesday 21 of August 2013 15:38:54 Lars Poeschel wrote:
>>
>>>>> To solve this dilemma, perform an interrupt consistency check
>>>>> when adding a GPIO chip: if the chip is both gpio-controller and
>>>>> interrupt-controller, walk all children of the device tree,
>>>
>>> It seems a little odd to solve this only for DT. What about the non-DT case?
>>
>> DT is the hardware configuration system that lets you request
>> the same resource in two ways, i.e. it allows one and the same
>> node to be both gpio-controller and interrupt-controller, and
>> start handing out the same line as both GPIO and IRQ
>> independently.
>
> Huh? What stops systems using board files and platform data from having
> this issue?

It can't be stopped but I consider it a bug if they do, as the proper
way to handle such GPIO lines is the sequence:

request_gpio(gpio);
request_irq(gpio_to_irq(gpio));

But I was mainly contrasting against ACPI, where the problem appears
to not exist.

Yours,
Linus Walleij
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