From owner-freebsd-arch@FreeBSD.ORG Sun Nov 23 18:34:49 2008 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id C507A1065673; Sun, 23 Nov 2008 18:34:49 +0000 (UTC) (envelope-from des@des.no) Received: from tim.des.no (tim.des.no [194.63.250.121]) by mx1.freebsd.org (Postfix) with ESMTP id 886438FC0A; Sun, 23 Nov 2008 18:34:49 +0000 (UTC) (envelope-from des@des.no) Received: from ds4.des.no (des.no [84.49.246.2]) by smtp.des.no (Postfix) with ESMTP id 9A58D6D43F; Sun, 23 Nov 2008 18:18:25 +0000 (UTC) Received: by ds4.des.no (Postfix, from userid 1001) id 67C428449F; Sun, 23 Nov 2008 19:18:25 +0100 (CET) From: =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= To: Nathan Whitehorn References: <4929877B.6060307@freebsd.org> Date: Sun, 23 Nov 2008 19:18:25 +0100 In-Reply-To: <4929877B.6060307@freebsd.org> (Nathan Whitehorn's message of "Sun, 23 Nov 2008 10:40:27 -0600") Message-ID: <86myfq9uha.fsf@ds4.des.no> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.0.60 (berkeley-unix) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Cc: freebsd-arch@freebsd.org Subject: Re: Enumerable I2C busses X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 23 Nov 2008 18:34:49 -0000 Nathan Whitehorn writes: > The current I2C bus mechanism does not support the bus adding its own > children [...] That's because the I2C protocol does not support device enumeration or identification. You have to know in advance what kind of devices are attached and at what address. Even worse, it is not uncommon for similar but not entirely compatible devices to use the same I2C address (for instance, every I2C-capable RTC chip uses the same address, even though they have different feature sets) DES --=20 Dag-Erling Sm=C3=B8rgrav - des@des.no