From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Brownell Subject: Re: [patch 2.6.22-git5 0/4] MMC-over-SPI Date: Mon, 6 Aug 2007 20:21:00 -0700 Message-ID: <200708062021.01241.david-b@pacbell.net> References: <200707141504.51950.david-b@pacbell.net> <20070723142923.GA28979@localhost.localdomain> <200707231033.31717.david-b@pacbell.net> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Cc: Hans-Peter Nilsson , Mikael Starvik , Mike Lavender , spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, Pierre Ossman To: avorontsov-hkdhdckH98+B+jHODAdFcQ@public.gmane.org Return-path: In-Reply-To: <200707231033.31717.david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org> Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: spi-devel-general-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: spi-devel-general-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-spi.vger.kernel.org On Monday 23 July 2007, David Brownell wrote: > > > If that hardware were doing the right thing, then it would work > > > reliably! =A0Since it's not reliable, it's doing something wrong. > > > You seem to think it's not a hardware issue; that may be true. > > > = > > > Recall that the first dozen or so commands worked just fine. =A0The > > > issue was that some byte that should have been all-ones or 0xfe > > > reported instead an 0xf8. =A0That's not the kind of error that can > > > be explained by clock skew; it covers at least two bits. > > = > > Yup, I've either noticed that 0xf8 and 0xfe differs by only two > > bits (and by three if comparing to 0xff). But I can't really > > explain it yet. Just for the record -- on my test rig, SPI mode 3 stopped working entirely ... I'd get one-bit errors, so that CMD0 status would be "0x03" instead of "0x01" (indicating CRC error plus still-resetting). Switching to SPI mode 0 made it all work again; masking out the 0x02 bit made everything time out. So I'm thinking that *was* somehow a shift of one bit. I think this was caused by removing wires for one SPI device from that breadboard ... but it's hard to say for sure. For a while it seemed like MMC cards worked OK but not SD cards! I'm working on a more permanent rig. But I think when I send the next revision to Pierre, it'll be using SPI_MODE_0. :) I thought you might be amused, given the strange behavior you saw! - Dave ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/