Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755435AbZD0UrV (ORCPT ); Mon, 27 Apr 2009 16:47:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752148AbZD0UrL (ORCPT ); Mon, 27 Apr 2009 16:47:11 -0400 Received: from az33egw02.freescale.net ([192.88.158.103]:48944 "EHLO az33egw02.freescale.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751629AbZD0UrK (ORCPT ); Mon, 27 Apr 2009 16:47:10 -0400 Message-ID: <49F619C4.20100@freescale.com> Date: Mon, 27 Apr 2009 15:47:00 -0500 From: Timur Tabi User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1b3pre) Gecko/20090327 SeaMonkey/2.0a3 MIME-Version: 1.0 To: Ira Snyder CC: David Hawkins , Liu Dave-R63238 , linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, Dan Williams , Kumar Gala 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> <20090427204213.GA4960@ovro.caltech.edu> In-Reply-To: <20090427204213.GA4960@ovro.caltech.edu> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAQAAAWE= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1442 Lines: 35 Adding Kumar to the CC: list, since he might pick up the patch. Ira Snyder wrote: > From 73e42fa58c93de8d4d429ba8e069b60c42037b58 Mon Sep 17 00:00:00 2001 > From: Ira W. Snyder > Date: Thu, 23 Apr 2009 16:17:54 -0700 > Subject: [PATCH] fsldma: use PCI Read Multiple command > > By default, the Freescale 83xx DMA controller uses the PCI Read Line > command when reading data over the PCI bus. Setting the controller to use > the PCI Read Multiple command instead allows the controller to read much > larger bursts of data, which provides a drastic speed increase. > > The slowdown due to using PCI Read Line was only observed when a PCI-to-PCI > bridge was between the devices trying to communicate. > > A simple test driver showed an increase from 4MB/sec to 116MB/sec when > performing DMA over the PCI bus. Using DMA to transfer between blocks of > local SDRAM showed no change in performance with this patch. The dmatest > driver was also used to verify the correctness of the transfers, and showed > no errors. > > Signed-off-by: Ira W. Snyder Acked-by: Timur Tabi -- Timur Tabi Linux kernel developer at Freescale -- 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/