From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751504AbWF1Rrn (ORCPT ); Wed, 28 Jun 2006 13:47:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751508AbWF1Rrn (ORCPT ); Wed, 28 Jun 2006 13:47:43 -0400 Received: from outpipe-village-512-1.bc.nu ([81.2.110.250]:18338 "EHLO lxorguk.ukuu.org.uk") by vger.kernel.org with ESMTP id S1751504AbWF1Rrm (ORCPT ); Wed, 28 Jun 2006 13:47:42 -0400 Subject: Re: [PATCH] (Longhaul 1/5) PCI: Protect bus master DMA from Longhaul by rw semaphores From: Alan Cox To: Greg KH Cc: Rafa? Bilski , linux-kernel@vger.kernel.org, davej@redhat.com In-Reply-To: <20060628173448.GA2371@suse.de> References: <44A28AA2.6060306@interia.pl> <20060628173448.GA2371@suse.de> Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: Wed, 28 Jun 2006 19:03:00 +0100 Message-Id: <1151517780.15166.52.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.6.2 (2.6.2-1.fc5.5) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Ar Mer, 2006-06-28 am 10:34 -0700, ysgrifennodd Greg KH: > Eeek! You mean the longhaul driver can change the frequency of the PCI > bus? Oh, that's a recipe for disaster... Not as I understand the docs, and that would be unfixable. Some C3 setups do however appear to "fall off the bus" during transitions which means if BMDMA is active things get confused. I am still not clear if this is just cache corruption through us not listening or whether we genuinely need to halt. In the former case flushing and disabling the CPU caches ought to be sufficient. Alan