From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Madhusudhan" Subject: RE: [PATCH-V2] OMAP: Fix for bus width which improves SD card's peformance. Date: Wed, 31 Mar 2010 11:37:19 -0500 Message-ID: <003b01cad0f0$6ea78040$544ff780@am.dhcp.ti.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=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: 'kishore kadiyala' , 'Vimal Singh' Cc: 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 > -----Original Message----- > From: kishore kadiyala [mailto:kishorek.kadiyala@gmail.com] > Sent: Wednesday, March 31, 2010 2:03 AM > To: Vimal Singh > Cc: Madhusudhan; tony@atomide.com; svenkatr@ti.com; linux- > omap@vger.kernel.org; linux-kernel@vger.kernel.org; > jarkko.lavinen@nokia.com > Subject: Re: [PATCH-V2] OMAP: Fix for bus width which improves SD car= d's > peformance. >=20 > Sorry for that and here's the Updated one. >=20 > From: Kishore Kadiyala >=20 > 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. >=20 > Signed-off-by: Kishore Kadiyala > Signed-off-by: Venkatraman S > Acked-by: Madhusudhan Chikkature >=20 > --- > In V2 : Appended Signed-off by Venkat and Ack by Madhu >=20 > Here are my experiment numbers, on a Class 6 SDHC card: > Read peformance is increased by 220% > Write Performance is increased by 52% >=20 > drivers/mmc/host/omap_hsmmc.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) >=20 > diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hs= mmc.c > index 83f0aff..8c97c22 100644 > --- a/drivers/mmc/host/omap_hsmmc.c > +++ b/drivers/mmc/host/omap_hsmmc.c > @@ -2092,7 +2092,7 @@ static int __init omap_hsmmc_probe(struct > MMC_CAP_WAIT_WHILE_BUSY; >=20 > if (mmc_slot(host).wires >=3D 8) > - mmc->caps |=3D MMC_CAP_8_BIT_DATA; > + mmc->caps |=3D (MMC_CAP_8_BIT_DATA | MMC_CAP_4_BIT_DATA); > else if (mmc_slot(host).wires >=3D 4) > mmc->caps |=3D MMC_CAP_4_BIT_DATA; >=20 Kishore, Since this patch is not yet pushed it makes sense to fix the readabilit= y issue. Since 8-bit is the max how about: =A0 =A0 =A0 =A0if (mmc_slot(host).wires =3D=3D 8) =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0mmc->caps |=3D MMC_CAP_8_BIT_DATA | MMC= _CAP_4_BIT_DATA; =A0 =A0 =A0 =A0if (mmc_slot(host).wires =3D=3D 4) =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0mmc->caps |=3D MMC_CAP_4_BIT_DATA; This would be little easy to read the code. Can you please repost the patch?? Regards, Madhu > -- > 1.6.3.3