From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2993276AbXDTQNQ (ORCPT ); Fri, 20 Apr 2007 12:13:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S2993275AbXDTQNQ (ORCPT ); Fri, 20 Apr 2007 12:13:16 -0400 Received: from usul.saidi.cx ([204.11.33.34]:53071 "EHLO usul.overt.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2993276AbXDTQNP (ORCPT ); Fri, 20 Apr 2007 12:13:15 -0400 Message-ID: <4628E68A.9000809@overt.org> Date: Fri, 20 Apr 2007 09:12:58 -0700 From: Philip Langdale User-Agent: Thunderbird 2.0.0.0 (X11/20070326) MIME-Version: 1.0 To: Madhusudhan c CC: Pierre Ossman , linux-kernel@vger.kernel.org References: <4625DAFC.4000208@drzeus.cx> <46262953.3040801@drzeus.cx> <462797EE.2050808@drzeus.cx> In-Reply-To: X-Enigmail-Version: 0.95.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-I-Got-Here: Yes X-I-Got-Here: Yes3 Subject: Re: MMCv4 support (8-bit support missing) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Madhusudhan c wrote: > > Suppose a host controller is capable of suporting 8-bit and it tells > the core that it can support 8-bit. Now the card that is plugged in > might or might not support 8-bit based on the type of the card. There > is no field in the ext_csd which will tell you what bus width the card > can support. My understanding is that 8-bit support on the card is not optional. ie: the card is not mmc 4 compliant if it doesn't support 8-bit and this is why there's no ext_csd field. The only case I could think of where bus testing would be needed would be if a controller was placed into a configuration where some pins were deliberately left unconnected (perhaps because space constraints prevented the extra 4 pins from being placed on a pcb) and there was no way to change the capabilities reported by the controller. But in any case - this is all hypothetical right now - one can't find a controller in the wild for love or money (well - Arasan will sell you a validation controller for $5000 but still...). As neither Pierre or myself is in a position to do any sort of tests on an 8-bit controller, we can't investigate or verify any of this. It certainly seems that you have access to an 8-bit controller. If you can help one or both of us get access to one, I'm sure we could work out the right thing to do. --phil