From: Grant Likely <grant.likely@secretlab.ca>
To: Andre Schwarz <andre.schwarz@matrix-vision.de>
Cc: linux-ppc list <linuxppc-dev@ozlabs.org>
Subject: Re: GPIO @ MPC5200
Date: Fri, 4 Jul 2008 08:36:19 -0600 [thread overview]
Message-ID: <20080704143619.GA15751@secretlab.ca> (raw)
In-Reply-To: <486DF3FA.3010806@matrix-vision.de>
On Fri, Jul 04, 2008 at 11:57:14AM +0200, Andre Schwarz wrote:
> Sascha, Grant,
>
> I'm running on 2.6.26-rc6 with an MPC5200B based system.
>
> Looks like some (for me) crucial GPIO are touched during boot.
> Is this possible ?
>
> Of course I have compiled in GPIO-Lib and specified the GPIOs in the dts.
> But no access yet - I'd like to preserve the setup from u-boot...
The GPIO driver only writes to the GPIO registers when a driver actually
requests to use them. At probe time, the gpio drivers read the current
values from the GPIO registers, so current config should be preserved.
However, the gpiochip_dir hook explicitly sets the output value when it
is called. It may be that when you are claiming the GPIO line it is
getting set with a default (and wrong) value.
Another possibility; have you verified that it is the GPIO regs getting
clobbered? Or is port_config getting changed on you? Which GPIO pins?
g.
next prev parent reply other threads:[~2008-07-04 14:37 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-04 9:57 GPIO @ MPC5200 Andre Schwarz
2008-07-04 14:36 ` Grant Likely [this message]
2008-07-04 15:10 ` Andre Schwarz
2008-07-04 15:58 ` Grant Likely
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