From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Madhusudhan" Subject: RE: [PATCH v3] OMAP: Fix for bus width which improves SD card's peformance. Date: Tue, 6 Apr 2010 11:16:01 -0500 Message-ID: <003901cad5a4$730264d0$544ff780@am.dhcp.ti.com> References: <004701caab40$68b576e0$544ff780@am.dhcp.ti.com> <003b01cad0f0$6ea78040$544ff780@am.dhcp.ti.com> <003c01cad1b1$da2cdbf0$544ff780@am.dhcp.ti.com> <20100405164839.GB17388@gandalf> <007c01cad4e4$26c5a700$544ff780@am.dhcp.ti.com> <20100406050035.GA32537@gandalf> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from bear.ext.ti.com ([192.94.94.41]:43888 "EHLO bear.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755845Ab0DFQQM (ORCPT ); Tue, 6 Apr 2010 12:16:12 -0400 In-Reply-To: <20100406050035.GA32537@gandalf> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: me@felipebalbi.com Cc: 'kishore kadiyala' , 'Vimal Singh' , tony@atomide.com, svenkatr@ti.com, linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org, jarkko.lavinen@nokia.com > -----Original Message----- > From: Felipe Balbi [mailto:me@felipebalbi.com] > Sent: Tuesday, April 06, 2010 12:01 AM > To: Madhusudhan > Cc: me@felipebalbi.com; 'kishore kadiyala'; 'Vimal Singh'; > tony@atomide.com; svenkatr@ti.com; linux-omap@vger.kernel.org; linux- > kernel@vger.kernel.org; jarkko.lavinen@nokia.com > Subject: Re: [PATCH v3] OMAP: Fix for bus width which improves SD card's > peformance. > > Hi, > > On Mon, Apr 05, 2010 at 12:19:29PM -0500, Madhusudhan wrote: > > Since the first if command already checks for the 8-bit the second check > > like >= 4 is definitely not readable in my opinion. > > how come ??? > > > Functionally do you see anything wrong with this patch?? > > functionally no, but (hypothetical situation) and if on > omap4/5/6/whatever, omap controller supports a bigger bus width then > you'll have to add a line like: > > + if (mmc_slot(host).wires == 16) > + mmc->caps |= (MMC_CAP_16_BIT_DATA | MMC_CAP_8_BIT_DATA | > + MMC_CAP_4_BIT_DATA); > - if (mmc_slot(host).wires == 8) > + else if (mmc_slot(host).wires == 8) > > do you see the problem ?? In my opinion it doesn't scale well. > The point we should note here is that MMC spec supports a max bus width of 8-bit. So anything beyond 8-bit is not in the picture as of today. But, my bad on miss interpreting the snippet Felipe sent earlier. if (mmc_slot(host).wires >= 8) mmc->caps |= MMC_CAP_8_BIT_DATA; if (mmc_slot(host).wires >= 4) mmc->caps |= MMC_CAP_4_BIT_DATA; I missed the fact that you removed the setting of 4-bit from the first check. I am okay with the above snippet as it is a trivial change that we are trying to patch here which fixes an important issue. Regards, Madhu > -- > balbi