linux-kernel - Re: [PATCH v3] gpio: interrupt consistency check for OF GPIO IRQs

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Date:	Tue, 03 Sep 2013 11:22:23 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	anish singh <anish198519851985@...il.com>
CC:	Linus Walleij <linus.walleij@...aro.org>,
	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>,
	Tomasz Figa <tomasz.figa@...il.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 v3] gpio: interrupt consistency check for OF GPIO IRQs

On 08/31/2013 09:32 AM, anish singh wrote:
> On Sat, Aug 31, 2013 at 1:23 AM, Stephen Warren <swarren@...dotorg.org
> <mailto:swarren@...dotorg.org>> wrote:

>     I still haven't seen an answer to why we really care about this; how
>     many times has code actually allocated the same GPIO/IRQ when it
>     shouldn't, in a way that it wasn't detectable by some other mechanism,
>     i.e. the feature just not working? Why are we even trying to solve this
>     issue? I'm not totally convinced it even makes sense to try and
>     solve it.
> 
>  
> Probably this issue(same gpio/irq being used by multiple drivers) is
> very rare
> but debugging it is bit difficult.

Really? It's easy to just look in /proc/interrupts and
/sys/kernel/debug/gpio.

> This generally happens when we are working
> on latest revised boards where latest gpio number of some driver
> conflicts with the some other driver.

At least in the DT case, which is all that this patch solves, the DT is
describing the HW GPIO/IRQ numbers, so the Linux GPIO numbers are
irrelevant; everything is expressed as raw HW numbers, which are quite
easy to check.
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