From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 16479 invoked by alias); 28 Oct 2009 13:04:21 -0000 Received: (qmail 16470 invoked by uid 22791); 28 Oct 2009 13:04:20 -0000 X-SWARE-Spam-Status: No, hits=-1.9 required=5.0 tests=AWL,BAYES_00,SPF_PASS X-Spam-Check-By: sourceware.org Received: from cheviot21.ncl.ac.uk (HELO cheviot21.ncl.ac.uk) (128.240.234.21) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Wed, 28 Oct 2009 13:04:15 +0000 Received: from cheviot21.ncl.ac.uk (localhost.localdomain [127.0.0.1]) by cheviot21.ncl.ac.uk (8.13.8/8.13.8) with ESMTP id n9SD4DsW000622 for ; Wed, 28 Oct 2009 13:04:13 GMT Received: from exhubct01.campus.ncl.ac.uk (exhubct01.ncl.ac.uk [10.8.239.5]) by cheviot21.ncl.ac.uk (cheviot21.ncl.ac.uk [128.240.234.73]) envelope-from with ESMTP id l9RD4D1968027607Nd ret-id none; Wed, 28 Oct 2009 13:04:13 +0000 Received: from EXSAN01.campus.ncl.ac.uk ([10.8.239.12]) by exhubct01.campus.ncl.ac.uk ([10.8.239.5]) with mapi; Wed, 28 Oct 2009 13:04:12 +0000 From: Steven Clugston To: "ecos-discuss@ecos.sourceware.org" Date: Wed, 28 Oct 2009 13:04:00 -0000 Message-ID: <4DCF6DBD3535F742BB167C528BBEE9803828B88A33@EXSAN01.campus.ncl.ac.uk> References: <4DCF6DBD3535F742BB167C528BBEE9803828B88A32@EXSAN01.campus.ncl.ac.uk>,<20091028123741.GA11133@lunn.ch> In-Reply-To: <20091028123741.GA11133@lunn.ch> Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-smtpf-Report: sid=l9RD4D196802760700; client=lan,relay,white,ipv6; mail=; rcpt=; nrcpt=1:0; fails=0 Mailing-List: contact ecos-discuss-help@ecos.sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: ecos-discuss-owner@ecos.sourceware.org Subject: RE: [ECOS] AT91 I2C driver X-SW-Source: 2009-10/txt/msg00170.txt.bz2 >> Is anybody out there interested in having/testing an AT91 I2C driver? >> >> I'm currently having a stab at writing one using the lpc2xxx one as >> a reference, although I'm not sure if I'll actually have time to see >> it through to completion yet. > A word of caution. The Linux kernel guys consider the AT91 I2C device > to be FOOBAR. > http://cateee.net/lkddb/web-lkddb/I2C_AT91.html > http://www.mail-archive.com/git-commits-head@vger.kernel.org/msg24797.html > http://www.mail-archive.com/i2c@lm-sensors.org/msg02209.html > I think it is O.K. for single byte transfers, but anything more than > that could lead to problems. > Maybe you should consider bit banging the pins? > Andrew Andrew, Thanks very much for pointing this out. It must explain why nobody has writ= ten the driver before. I was in two minds whether to just try the generic bit bang driver instead,= but I thought it was worth an attempt at using the chip's hardware first p= articularly if anybody else was interested. I've shot myself in the foot now because it turns out I do need multi-byte = transfers and I've used a part that has a timeout of 35ms on the clock whic= h might make bit-bang problematic if its too slow for some reason. Steven -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss