From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from p15137414.pureserver.info (matrixvision.de [217.160.213.229]) by ozlabs.org (Postfix) with ESMTP id 4A2DFDDD0B for ; Sat, 5 Jul 2008 01:10:50 +1000 (EST) Message-ID: <486E3D76.5090207@matrix-vision.de> Date: Fri, 04 Jul 2008 17:10:46 +0200 From: Andre Schwarz MIME-Version: 1.0 To: Grant Likely Subject: Re: GPIO @ MPC5200 References: <486DF3FA.3010806@matrix-vision.de> <20080704143619.GA15751@secretlab.ca> In-Reply-To: <20080704143619.GA15751@secretlab.ca> Content-Type: text/plain; charset=ISO-8859-1 Cc: linux-ppc list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Grant Likely schrieb: > 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. > The pin in question is PSC2_4, i.e. a wake-up GPIO. It is configured as push-pull output and driven high. Since it has an external pull-down resistor I can't say if it is driven low or re-configured as an input ... I removed GPIO Lib and the problem is gone. I'm not yet using it anyway under linux - they're mainly for system configuration (setting up muxes etc.). I'll dig into it when I have some time. thanks, Andre MATRIX VISION GmbH, Talstraße 16, DE-71570 Oppenweiler - Registergericht: Amtsgericht Stuttgart, HRB 271090 Geschäftsführer: Gerhard Thullner, Werner Armingeon, Uwe Furtner