Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752076Ab0DSPgs (ORCPT ); Mon, 19 Apr 2010 11:36:48 -0400 Received: from fg-out-1718.google.com ([72.14.220.156]:20089 "EHLO fg-out-1718.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750715Ab0DSPgq (ORCPT ); Mon, 19 Apr 2010 11:36:46 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=e5Gd7eANC0KgTZM0BvKn77FKpFyv3jAtTJ5ZYRk7kdNOYfNFQyaFT9UhPN3p2sEtF4 OsWjAzNwF5VXs/m5J3lDMCkVnjss1giOQw0MGo6C4xgD/sGcIsAB79xI94l2udnTkEQ2 nYJnY48LKje0rxqZBbgUQHyu9D1G0QyA10r0k= MIME-Version: 1.0 In-Reply-To: <003601cad73c$98c3aa50$544ff780@am.dhcp.ti.com> References: <003b01cad0f0$6ea78040$544ff780@am.dhcp.ti.com> <003901cad5a4$730264d0$544ff780@am.dhcp.ti.com> <20100406163211.GA29117@nokia.com> <4BBB6767.7010202@ti.com> <20100406165720.GA17916@nokia.com> <00b401cad5e0$1d1868d0$544ff780@am.dhcp.ti.com> <4BBBC628.9030207@ti.com> <00c901cad5e7$9de54350$544ff780@am.dhcp.ti.com> <4BBBD87C.1040307@ti.com> <003601cad73c$98c3aa50$544ff780@am.dhcp.ti.com> Date: Mon, 19 Apr 2010 21:06:36 +0530 Message-ID: Subject: [PATCH v4] OMAP: Fix for bus width which improves SD card's peformance. From: kishore kadiyala To: Madhusudhan Cc: Nishanth Menon , felipe.balbi@nokia.com, me@felipebalbi.com, Vimal Singh , tony@atomide.com, "S, Venkatraman" , linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org, "Lavinen Jarkko (Nokia-D/Helsinki)" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2376 Lines: 66 From: Kishore Kadiyala 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 Signed-off-by: Nishant Menon Acked-by: Madhusudhan Chikkature Tested-by: Jarkko Nikula --- In V4 : Updated with Nishant's comments and appened his Signed-off In V3 : Updated with Madhu's comments and appended Tested by Nikula 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% drivers/mmc/host/omap_hsmmc.c | 19 ++++++++++++++++--- 1 files changed, 16 insertions(+), 3 deletions(-) diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c index 8c97c22..9c1a60e 100644 --- a/drivers/mmc/host/omap_hsmmc.c +++ b/drivers/mmc/host/omap_hsmmc.c @@ -2091,10 +2091,23 @@ static int __init omap_hsmmc_probe(struct platform_device *pdev) mmc->caps |= MMC_CAP_MMC_HIGHSPEED | MMC_CAP_SD_HIGHSPEED | MMC_CAP_WAIT_WHILE_BUSY; - if (mmc_slot(host).wires >= 8) - mmc->caps |= (MMC_CAP_8_BIT_DATA | MMC_CAP_4_BIT_DATA); - else if (mmc_slot(host).wires >= 4) + switch (mmc_slot(host).wires) { + case 8: + mmc->caps |= MMC_CAP_8_BIT_DATA; + /* Fall through */ + case 4: mmc->caps |= MMC_CAP_4_BIT_DATA; + break; + case 1: + /* Nothing to crib here */ + case 0: + /* Assuming nothing was given by board, Core use's 1-Bit */ + break; + default: + /* Completely unexpected.. Core goes with 1-Bit Width */ + dev_crit(mmc_dev(host->mmc), "Invalid width %d\n used!" + "using 1 instead\n", mmc_slot(host).wires); + } if (mmc_slot(host).nonremovable) mmc->caps |= MMC_CAP_NONREMOVABLE; -- 1.6.3.3 -- 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/