From mboxrd@z Thu Jan  1 00:00:00 1970
From: sebastian.hesselbarth@googlemail.com (Sebastian Hesselbarth)
Date: Thu, 05 Jul 2012 14:09:59 +0200
Subject: [PATCH v2 01/12] ARM: Orion: DT support for IRQ and GPIO
 Controllers
In-Reply-To: <20120705114815.GT17534@lunn.ch>
References: <1341325365-21393-1-git-send-email-andrew@lunn.ch>
 <1341325365-21393-2-git-send-email-andrew@lunn.ch>
 <20120705110251.596331e0@skate> <20120705094824.GO17534@lunn.ch>
 <87sjd6ikkj.fsf@lebrac.rtp-net.org> <20120705122050.2fbc2fe3@skate>
 <87liiyijb8.fsf@lebrac.rtp-net.org> <20120705134231.3e1801e5@skate>
 <20120705114815.GT17534@lunn.ch>
Message-ID: <4FF58417.8050001@googlemail.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 07/05/2012 01:48 PM, Andrew Lunn wrote:
 >> Yes. I am not sure yet how to describe those in the DT, or even if it
 >> is actually useful to describe them. Wouldn't it be simpler to just
 >> leave to the user of the GPIO to use a GPIO that's appropriate for its
 >> usage, i.e not use a GPO when input is needed?
 >
 > We assume the hardware designer has got the basic hardware right. Its
 > not going to work otherwise.
 >
 > What we are trying to detect is a DT author making a typo, assigning a
 > gpio-key to a GPO pin, for example. The current MPP scheme will detect
 > this sort of error and issue a warning to the kernel logs.

The output-only/non-interrupt gpios could be marked as such in DT.
The common code should not install irqs if marked by e.g.
"marvell,gpio-no-irq". The gpio driver already fails to set input
direction on output-only pins. This could be marked by e.g.
"marvell,gpio-output-only" in DT.

Sebastian