From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Madhusudhan" Subject: RE: [PATCH v4] OMAP: Fix for bus width which improves SD card's peformance. Date: Wed, 21 Apr 2010 19:26:00 -0500 Message-ID: <008f01cae1b2$6262c970$544ff780@am.dhcp.ti.com> References: <003b01cad0f0$6ea78040$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> 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: '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)'" List-Id: linux-omap@vger.kernel.org > -----Original Message----- > From: kishore kadiyala [mailto:kishorek.kadiyala@gmail.com] > Sent: Monday, April 19, 2010 10:52 AM > 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) > Subject: [PATCH v4] OMAP: Fix for bus width which improves SD card's > peformance. > > The previous patch was Line wrapped , resending > correct patch. > NM, Sorry I miss spelled your name correcting this time. > > Regards, > Kishore > Tony, I don't see any further comments on this patch. Can you please push this patch? Regards, Madhu > 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: Nishanth 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 > 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