From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758186Ab1I3IqI (ORCPT ); Fri, 30 Sep 2011 04:46:08 -0400 Received: from smtprelay06.ispgateway.de ([80.67.31.102]:58370 "EHLO smtprelay06.ispgateway.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754967Ab1I3IqG (ORCPT ); Fri, 30 Sep 2011 04:46:06 -0400 Message-ID: <4E858200.8070302@ladisch.de> Date: Fri, 30 Sep 2011 10:46:56 +0200 From: Clemens Ladisch User-Agent: Thunderbird 2.0.0.24 (Windows/20100228) MIME-Version: 1.0 To: markh@compro.net CC: "linux-pci@vger.kernel.org" , Linux-kernel , Mark Hounschell Subject: Re: Problem with AMD chipsets. Was "Re: problems doing direct dma from a pci device to pci-e device" References: <4E84CA01.2060907@compro.net> <4E84D55A.5050406@compro.net> In-Reply-To: <4E84D55A.5050406@compro.net> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Df-Sender: bGludXgta2VybmVsQGNsLmRvbWFpbmZhY3Rvcnkta3VuZGUuZGU= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Mark Hounschell wrote: > We have no problem with this same configuration using a MB with an > nvidia chipset. I suspect it might have something to do with the the MB > that usines the AMD chipset having an IOMMU, but I really don't know for > sure. I've also read something in the AMD chipset docs about some type > of restrictions on peer to peer transfers but again I really have no > idea if this is related to why I'm having this problem. According to the published RS780 docs, "P2P traffic could be only memory writes" (RPR 2.7). In any case, check the P2P bits (MISC is described in BDG 2.4). Regards, Clemens