From mboxrd@z Thu Jan 1 00:00:00 1970 From: kishore kadiyala Subject: Re: [PATCH-V2] OMAP: Fix for bus width which improves SD card's peformance. Date: Thu, 1 Apr 2010 12:01:49 +0530 Message-ID: References: <35697.192.168.10.89.1265898023.squirrel@dbdmail.itg.ti.com> <004701caab40$68b576e0$544ff780@am.dhcp.ti.com> <003b01cad0f0$6ea78040$544ff780@am.dhcp.ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail-fx0-f227.google.com ([209.85.220.227]:57103 "EHLO mail-fx0-f227.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753486Ab0DAGbw convert rfc822-to-8bit (ORCPT ); Thu, 1 Apr 2010 02:31:52 -0400 In-Reply-To: <003b01cad0f0$6ea78040$544ff780@am.dhcp.ti.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Madhusudhan Cc: Vimal Singh , tony@atomide.com, svenkatr@ti.com, linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org, jarkko.lavinen@nokia.com On Wed, Mar 31, 2010 at 10:07 PM, Madhusudhan wrote: > > >> -----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 ca= rd's >> peformance. >> >> Sorry for that and here's the Updated one. >> >> 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 >> Acked-by: Madhusudhan Chikkature >> >> --- >> In V2 : Appended Signed-off by Venkat and Ack by Madhu >> >> =A0Here are my experiment numbers, on a Class 6 SDHC card: >> =A0Read peformance is increased by 220% >> =A0Write Performance is increased by 52% >> >> =A0drivers/mmc/host/omap_hsmmc.c | =A0 =A02 +- >> =A01 files changed, 1 insertions(+), 1 deletions(-) >> >> diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_h= smmc.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 >> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0MMC_CAP_WAIT_WHILE_BUSY; >> >> =A0 =A0 =A0 if (mmc_slot(host).wires >=3D 8) >> - =A0 =A0 =A0 =A0 =A0 =A0 mmc->caps |=3D MMC_CAP_8_BIT_DATA; >> + =A0 =A0 =A0 =A0 =A0 =A0 mmc->caps |=3D (MMC_CAP_8_BIT_DATA | MMC_C= AP_4_BIT_DATA); >> =A0 =A0 =A0 else if (mmc_slot(host).wires >=3D 4) >> =A0 =A0 =A0 =A0 =A0 =A0 =A0 mmc->caps |=3D MMC_CAP_4_BIT_DATA; >> > Kishore, > > Since this patch is not yet pushed it makes sense to fix the readabil= ity > issue. > > Since 8-bit is the max how about: > > =A0=A0 =A0 =A0 =A0if (mmc_slot(host).wires =3D=3D 8) > =A0=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0mmc->caps |=3D MMC_CAP_8_BIT_DATA |= MMC_CAP_4_BIT_DATA; > =A0=A0 =A0 =A0 =A0if (mmc_slot(host).wires =3D=3D 4) > =A0=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0mmc->caps |=3D MMC_CAP_4_BIT_DATA; > Madhu, In the above snippet, it checks whether wires are 8 or 4 and if not neither set's capability to "1". Does it make sense to check whether the wires are 8,4,1 and if not any[8,4,1] throw error and come out. Regards, Kishore > This would be little easy to read the code. > > Can you please repost the patch?? > > Regards, > Madhu > >> -- >> 1.6.3.3 > > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html