From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755789AbYICOLS (ORCPT ); Wed, 3 Sep 2008 10:11:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752504AbYICOLG (ORCPT ); Wed, 3 Sep 2008 10:11:06 -0400 Received: from server.drzeus.cx ([85.8.24.28]:40223 "EHLO smtp.drzeus.cx" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753531AbYICOLE (ORCPT ); Wed, 3 Sep 2008 10:11:04 -0400 Date: Wed, 3 Sep 2008 16:11:02 +0200 From: Pierre Ossman To: Sascha Hauer Cc: linux-kernel@vger.kernel.org Subject: Re: [MMC] Multiple cards on one host Message-ID: <20080903161102.004f6f9e@mjolnir.drzeus.cx> In-Reply-To: <20080903084343.GF4941@pengutronix.de> References: <20080903084343.GF4941@pengutronix.de> X-Mailer: Claws Mail 3.4.0 (GTK+ 2.13.7; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 3 Sep 2008 10:43:43 +0200 Sascha Hauer wrote: > Hi, > > I have a board (PXA based) which has two SD slots. It uses a gpio to > switch between the slots. In times when the MMC subsystem implemented > the bus topology our customer used this fact to connect the two slots on > a single host (although it was never intended to work with SD cards, it > seemed to work). Any idea how to implement this on recent kernels? I > thought about registering two hosts in pxamci.c, but this seems quite > hacky and I suppose I'll run into locking trouble. > To be honest, I don't think you can sanely support it. The OMAP guys have been playing with some kind of multiplexer in front of the controller, but it just seems like a world of hurt to me. Perhaps you can convert to using SPI for the second slot if the customer really needs a design with two slots? Rgds -- -- Pierre Ossman Linux kernel, MMC maintainer http://www.kernel.org rdesktop, core developer http://www.rdesktop.org WARNING: This correspondence is being monitored by the Swedish government. Make sure your server uses encryption for SMTP traffic and consider using PGP for end-to-end encryption.