From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753470AbYICQu0 (ORCPT ); Wed, 3 Sep 2008 12:50:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752077AbYICQuP (ORCPT ); Wed, 3 Sep 2008 12:50:15 -0400 Received: from metis.extern.pengutronix.de ([83.236.181.26]:55502 "EHLO metis.extern.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752005AbYICQuO (ORCPT ); Wed, 3 Sep 2008 12:50:14 -0400 Date: Wed, 3 Sep 2008 18:50:11 +0200 From: Sascha Hauer To: Pierre Ossman Cc: linux-kernel@vger.kernel.org Subject: Re: [MMC] Multiple cards on one host Message-ID: <20080903165011.GG4941@pengutronix.de> References: <20080903084343.GF4941@pengutronix.de> <20080903161102.004f6f9e@mjolnir.drzeus.cx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080903161102.004f6f9e@mjolnir.drzeus.cx> X-Sent-From: Pengutronix Entwicklungszentrum Nord - Hildesheim X-URL: http://www.pengutronix.de/ X-IRC: #ptxdist @freenode X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-Impressum: Pengutronix - Linux Solutions for Science and Industry Handelsregister: Amtsgericht Hildesheim, HRA 2686 Hannoversche Str. 2, 31134 Hildesheim, Germany Phone: +49-5121-206917-0 | Fax: +49-5121-206917-9 Inhaber: Dipl.-Ing. Robert Schwebel X-Message-Flag: See Message Headers for Impressum X-Uptime: 16:42:57 up 78 days, 17 min, 53 users, load average: 0.07, 0.04, 0.07 User-Agent: Mutt/1.5.17+20080114 (2008-01-14) X-SA-Exim-Connect-IP: 10.1.1.3 X-SA-Exim-Mail-From: sha@pengutronix.de X-SA-Exim-Scanned: No (on metis.extern.pengutronix.de); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 03, 2008 at 04:11:02PM +0200, Pierre Ossman wrote: > 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. That's what I was afraid of. Lets see what our customer says (I hope I won't find myself in this world of hurt) > > Perhaps you can convert to using SPI for the second slot if the > customer really needs a design with two slots? Might be an option. Thanks for your answer. Sascha -- Pengutronix - Linux Solutions for Science and Industry Handelsregister: Amtsgericht Hildesheim, HRA 2686 Hannoversche Str. 2, 31134 Hildesheim, Germany Phone: +49-5121-206917-0 | Fax: +49-5121-206917-9