From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753152AbXLDK5z (ORCPT ); Tue, 4 Dec 2007 05:57:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752298AbXLDK5s (ORCPT ); Tue, 4 Dec 2007 05:57:48 -0500 Received: from smtp4-g19.free.fr ([212.27.42.30]:33343 "EHLO smtp4-g19.free.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752068AbXLDK5r (ORCPT ); Tue, 4 Dec 2007 05:57:47 -0500 Message-ID: <475532A7.1000408@free.fr> Date: Tue, 04 Dec 2007 11:57:43 +0100 From: John Sigler User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.0.8) Gecko/20061108 SeaMonkey/1.0.6 MIME-Version: 1.0 To: linux-kernel@vger.kernel.org, linux-pci@atrey.karlin.mff.cuni.cz Subject: Is the PCI clock within the spec? Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello everyone, I have an x86 system, running Linux 2.6.22.1-rt9, in which I plug one or two PCI I/O boards. I had been experiencing complete system lock-ups until I sent the system to the board manufacturer, and he fixed the problem. However, he told me that the PCI clock seemed out of spec, as far as voltage is concerned. (Disclaimer: my knowledge of PCI is 0.) The board manufacturer sent me the plot of (what appears to be) voltage versus time for the PCI clock. http://linux.kernel.free.fr/plot1.jpg The system manufacturer sent me a similar plot. http://linux.kernel.free.fr/plot2.jpg As far as my understanding goes, the signal should alternate between 0 V and 3.3 V (??). In the second plot, it looks like Vmax ~ 4.6V and Vmin ~ -1.4V (Pk-Pk(C1)=6.08V might mean peak-to-peak voltage?) 0) What is this C1 both plots mention? 1) Am I reading the plot correctly? 2) Is -1.4V in DC even possible? 3) 4.6V is 1.3V above 3.3V and -1.4V is -1.4V below 0. (Assuming I read the numbers correctly) Are these values within the PCI spec? Or are these voltages dangerous and / or might cause some problems with some PCI boards? Regards.