Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764577AbZFQH62 (ORCPT ); Wed, 17 Jun 2009 03:58:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754272AbZFQH6V (ORCPT ); Wed, 17 Jun 2009 03:58:21 -0400 Received: from mail.oxtel.com ([193.200.114.15]:4962 "EHLO oxtel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754110AbZFQH6U (ORCPT ); Wed, 17 Jun 2009 03:58:20 -0400 Message-ID: <4A38A21B.5060306@oxtel.com> Date: Wed, 17 Jun 2009 08:58:19 +0100 From: Chris Pringle User-Agent: Thunderbird 2.0.0.21 (X11/20090409) MIME-Version: 1.0 To: Scott Wood CC: linux-kernel@vger.kernel.org, "linuxppc-dev@ozlabs.org list" Subject: Re: PowerPC PCI DMA issues (prefetch/coherency?) References: <4A37A503.3030209@oxtel.com> <20090616162114.GA5051@loki.buserror.net> <4A37C97A.5050508@oxtel.com> <4A37CC72.3060709@freescale.com> <4A37CF02.5080906@oxtel.com> <4A37D073.6020802@freescale.com> In-Reply-To: <4A37D073.6020802@freescale.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated-Sender: chris.pringle X-Server: VPOP3 Enterprise V2.6.0b - Registered Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1298 Lines: 41 > You could enable CONFIG_NOT_COHERENT_CACHE. > I've just tried this (I had to edit Kconfig in power/platforms to make the build system accept it), and interestingly it's making no difference. I'm using streaming mappings, and are using the pci_map_sg functions to ensure the memory is mapped/flushed correctly. I've also explicitly put in a pci_dma_sync_sg_for_device, however that's also not made any difference. Turning the cpu cache snoop off has the same affect as it did without CONFIG_NOT_COHERENT_CACHE; it gets much worse. Any other ideas? Will back off the low latency patches next, and give 2.6.30 a try - see if that makes any difference. -- ______________________________ Chris Pringle Software Engineer Miranda Technologies Ltd. Hithercroft Road Wallingford Oxfordshire OX10 9DG UK Tel. +44 1491 820206 Fax. +44 1491 820001 www.miranda.com ____________________________ Miranda Technologies Limited Registered in England and Wales CN 02017053 Registered Office: James House, Mere Park, Dedmere Road, Marlow, Bucks, SL7 1FJ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/