From mboxrd@z Thu Jan  1 00:00:00 1970
From: LW@KARO-electronics.de (Lothar =?UTF-8?B?V2HDn21hbm4=?=)
Date: Wed, 4 Dec 2013 10:13:16 +0100
Subject: [PATCH] ARM: dts: i.MX27: Configure GPIOs as "input" by default
In-Reply-To: <1386147840.110296074@f57.i.mail.ru>
References: <1385795000-29764-1-git-send-email-shc_work@mail.ru>
 <20131203133045.GC28465@pengutronix.de>
 <20131204095703.236ccbe0@ipc1.ka-ro>
 <1386147840.110296074@f57.i.mail.ru>
Message-ID: <20131204101316.2011e210@ipc1.ka-ro>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

Hi,

Alexander Shiyan wrote:
> > > On Tue, Dec 03, 2013 at 04:46:27PM +0800, Shawn Guo wrote:
> > > > On Sat, Nov 30, 2013 at 11:03:20AM +0400, Alexander Shiyan wrote:
> > > > > This patch changes the default direction for pins used
> > > > > as GPIO to "input". This prevents a short circuit on the
> > > > > configuration stage when GPIO-pin is connected to the
> > > > > other output pin.
> > > > 
> > > > Markus,
> > > > 
> > > > Does it make sense to you?
> > > 
> > > I am not sure if this really happens. However, it does make sense and I
> > > can't see any disadvantages in changing the default GPIO mux direction to
> > > input.
> > > 
> > What happens, if the bootloader already set up a pin as output and
> > linux later does the pinconfig stuff?
> > If the pin is reconfigured as input then, this may produce an unwanted
> > glitch on the pin. IMO the pinconfig driver should not touch the pin
> > direction, but leave it to the gpio driver to set that up. 
> 
> Such pin can be overridden by board DTS.
> 
So, which pins will be configured with the default direction?
If pins are not stated in DT they should be not configured at all, I
suppose.


Lothar Wa?mann
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