Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761502AbZD0Ulu (ORCPT ); Mon, 27 Apr 2009 16:41:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757818AbZD0Ulj (ORCPT ); Mon, 27 Apr 2009 16:41:39 -0400 Received: from ovro.ovro.caltech.edu ([192.100.16.2]:53683 "EHLO ovro.ovro.caltech.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755285AbZD0Ulj (ORCPT ); Mon, 27 Apr 2009 16:41:39 -0400 Message-ID: <49F6187F.8020703@ovro.caltech.edu> Date: Mon, 27 Apr 2009 13:41:35 -0700 From: David Hawkins User-Agent: Thunderbird 2.0.0.21 (Windows/20090302) MIME-Version: 1.0 To: Timur Tabi CC: Liu Dave-R63238 , Ira Snyder , linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, Dan Williams Subject: Re: [PATCH] fsldma: use PCI Read Multiple command References: <20090424183517.GB23140@ovro.caltech.edu> <49F608B7.9080409@ovro.caltech.edu> <49F60A3A.4060402@freescale.com> <49F61416.8040501@ovro.caltech.edu> <49F614FC.70000@freescale.com> In-Reply-To: <49F614FC.70000@freescale.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (ovro.ovro.caltech.edu); Mon, 27 Apr 2009 13:41:38 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1178 Lines: 32 Hi Timur, >> PRC_RM - PCI read multiple >> The default PCI read command used by the DMA controller is >> PCI Read (PCI command 6h). When the burst length is 32-bytes >> or longer, PCI Read Line (PCI command Eh) is used (undocumented >> feature of the controller). Using PCI read multiple >> (PCI command Ch) results in high-performance across PCI >> bridges. DMA transfers to non-prefetchable PCI registers >> should not result in prefetched reads, even when using >> the PCI read multiple command. > > I was thinking more along the lines of: > > "This driver tells the DMA controller to use the PCI Read Multiple > command, instead of the PCI Read Line command, for PCI read operations. > Please be aware that this setting may result in read pre-fetching on > some platforms." Ok, thanks. Ira will add your comment to the body of the code near the PRC_RM command and submit a new patch. Cheers, Dave -- 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/