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Date: Mon, 11 Nov 2013 19:28:37 +0100
From: Gerlando Falauto <gerlando.falauto@...mile.com>
To: Mark Brown <broonie@...nel.org>
CC: Stephen Warren <swarren@...dotorg.org>,
Lars Poeschel <poeschel@...onage.de>,
Javier Martinez Canillas <javier.martinez@...labora.co.uk>,
Linus Walleij <linus.walleij@...aro.org>,
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>,
Kumar Gala <galak@...eaurora.org>,
Pawel Moll <pawel.moll@....com>,
Tomasz Figa <tomasz.figa@...il.com>,
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
Hi everyone,
[jumping in on an old discussion]
On 09/09/2013 06:19 PM, Mark Brown wrote:
> On Wed, Sep 04, 2013 at 02:16:36PM -0600, Stephen Warren wrote:
>> On 09/04/2013 03:05 AM, Lars Poeschel wrote:
>
>>> The driver that tries to use the GPIO requested by this patch before HAS to
>>> fail. This is exactly the intention of this patch. We don't want the GPIO to
>>> be requested any more, if it is used as an interrupt pin.
>
>> That will break existing drivers. There are drivers that request the
>> same GPIO and IRQ. IIRC, the SDHCI CD (Card Detect) GPIO is requested
>> that way.
>
> Yes, plus input devices and audio jack detection among others. This
> pattern is very common if the GPIO is actually being used as a GPIO, an
> edge triggered interrupt is used to flag when something happens and the
> state is determined by reading the GPIO state (often with some
> debounce).
I actually came across this thread while looking for an answer to the
following (apparently trivial) question:
If you were to write a new driver & binding, what would be, in general,
the recommended DT binding for a cascade interrupt controller (or any
other peripheral, for that matter), which is connected through a GPIO
(to be used as IRQ)?
a) Through gpios = <&gpio0 N>
b) through interrupt-parent = <&gpio0> & interrupts <N
IRQ_TYPE_LEVEL_LOW>, or
c) both?
Thanks!
Gerlando
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