From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarkko Nikula Subject: Re: [PATCH-V2] OMAP: Fix for bus width which improves SD card's peformance. Date: Wed, 31 Mar 2010 16:11:53 +0300 Message-ID: <20100331161153.73d687ee.jhnikula@gmail.com> References: <35697.192.168.10.89.1265898023.squirrel@dbdmail.itg.ti.com> <004701caab40$68b576e0$544ff780@am.dhcp.ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: kishore kadiyala Cc: Vimal Singh , Madhusudhan , tony@atomide.com, svenkatr@ti.com, linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org, jarkko.lavinen@nokia.com List-Id: linux-omap@vger.kernel.org On Wed, 31 Mar 2010 12:33:01 +0530 kishore kadiyala wrote: > This patch improves low speeds for SD cards. > OMAP-MMC controller's can support maximum bus width of '8'. > when bus width is mentioned as "8" in controller data,the SD > stack will check whether bus width is "4" and if not it will > set bus width to "1" and there by degrading performance. > This patch fixes the issue and improves the performance of > SD cards. > > Signed-off-by: Kishore Kadiyala > Signed-off-by: Venkatraman S > Acked-by: Madhusudhan Chikkature > > --- > In V2 : Appended Signed-off by Venkat and Ack by Madhu > > Here are my experiment numbers, on a Class 6 SDHC card: > Read peformance is increased by 220% > Write Performance is increased by 52% > Some results from the BeagleBoard and 2 GB SD card: sync; time (dd if=/dev/zero of=`date +%s`.bin bs=1M count=100; sync) -> ~40 % improvement over 4 writes. time dd if=12700xxxxx.bin of=/dev/null -> ~96 % improvement over 4 reads. Feel free to add my tested-by. Tested-by: Jarkko Nikula