From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Stephen Schwarm, CSDP" Subject: simple sd card performance bug fix on OMAP Date: Fri, 28 May 2010 15:05:00 -0400 Message-ID: <4C0013DC.6060601@earthlink.net> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="------------030502080906080409030806" Return-path: Received: from elasmtp-dupuy.atl.sa.earthlink.net ([209.86.89.62]:38356 "EHLO elasmtp-dupuy.atl.sa.earthlink.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752631Ab0E1TkK (ORCPT ); Fri, 28 May 2010 15:40:10 -0400 Received: from [173.14.164.189] (helo=[192.168.3.100]) by elasmtp-dupuy.atl.sa.earthlink.net with esmtpa (Exim 4.67) (envelope-from ) id 1OI4rd-0008WB-9J for linux-omap@vger.kernel.org; Fri, 28 May 2010 15:05:01 -0400 Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: "linux-omap@vger.kernel.org" This is a multi-part message in MIME format. --------------030502080906080409030806 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit I have not had time to make a formal patch for this but I thought it was significant enough just to send it out. The problem is on omap systems that use omap_hsmmc.c to run sd or mmc cards. If the system you are using has an 8 wire interface, it will only use a one wire interface to 4 wire cards (eg, sd class 4 and sd class 6). In the file driver/mmc/omap_hsmmc.c in the function omap_hsmmc_probe: at about line 1739 change: if (mmc_slot(host).wires >= 8) mmc->caps |= MMC_CAP_8_BIT_DATA; else if (mmc_slot(host).wires >= 4) mmc->caps |= MMC_CAP_4_BIT_DATA; to: if (mmc_slot(host).wires >= 8) mmc->caps |= MMC_CAP_8_BIT_DATA; if (mmc_slot(host).wires >= 4) mmc->caps |= w; just delete the word "else". This sets the MMC_CAP_4_BIT_DATA bit on interfaces that have 8 wire interfaces. We have seen a BIG performance improvement on our systems. Steve Schwarm --------------030502080906080409030806 Content-Type: text/x-vcard; charset=utf-8; name="w3eve.vcf" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="w3eve.vcf" begin:vcard fn:Stephen Schwarm, CSDP n:Schwarm, CSDP;Stephen adr;dom:;;30 Hayden Woods;Wrentham;MA;02093 email;internet:schwarm@ieee.org tel;home:508-384-7697 tel;cell:508-922-9688 x-mozilla-html:FALSE version:2.1 end:vcard --------------030502080906080409030806--