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

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Message-Id: <201308231151.18075.poeschel@lemonage.de>
Date:	Fri, 23 Aug 2013 11:51:18 +0200
From:	Lars Poeschel <poeschel@...onage.de>
To:	Stephen Warren <swarren@...dotorg.org>
Cc:	Linus Walleij <linus.walleij@...aro.org>,
	Tomasz Figa <tomasz.figa@...il.com>,
	Lars Poeschel <larsi@....tu-dresden.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>, 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 Thursday 22 August 2013 at 22:53:09, Stephen Warren 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?

I am not 100% sure, Linus knows better.
I think nothing stops them from having this issue, but board files are 
gentle and request the GPIO before doing gpio_to_irq, because they know 
that they are using a gpio based interrupt.

You can read the whole story here:
http://www.mail-archive.com/linux-omap@vger.kernel.org/msg91405.html
Things get interesting after the first mail from Alexander Holler, who is 
the first having a problem with the patch in the link.
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