From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756601Ab2LNQGz (ORCPT ); Fri, 14 Dec 2012 11:06:55 -0500 Received: from avon.wwwdotorg.org ([70.85.31.133]:33929 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756417Ab2LNQGx (ORCPT ); Fri, 14 Dec 2012 11:06:53 -0500 Message-ID: <50CB4E99.9060506@wwwdotorg.org> Date: Fri, 14 Dec 2012 09:06:49 -0700 From: Stephen Warren User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Naveen Krishna Chatradhi CC: linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, linux-samsung-soc@vger.kernel.org, grundler@chromium.org, devicetree-discuss@lists.ozlabs.org, broonie@opensource.wolfsonmicro.com, w.sang@pengutronix.de, ben-linux@fluff.org, khali@linux-fr.org, naveen@chromium.org Subject: Re: [PATCH 1/2] i2c-core: Add gpio based bus arbitration implementation References: <1355464254-12768-1-git-send-email-ch.naveen@samsung.com> <1355464254-12768-2-git-send-email-ch.naveen@samsung.com> In-Reply-To: <1355464254-12768-2-git-send-email-ch.naveen@samsung.com> X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/13/2012 10:50 PM, Naveen Krishna Chatradhi wrote: > The arbitrator is a general purpose function which uses two GPIOs to > communicate with another device to claim/release a bus. > diff --git a/Documentation/devicetree/bindings/i2c/arbitrator-i2c.txt b/Documentation/devicetree/bindings/i2c/arbitrator-i2c.txt > new file mode 100644 > index 0000000..cb91ea8 > --- /dev/null > +++ b/Documentation/devicetree/bindings/i2c/arbitrator-i2c.txt > @@ -0,0 +1,56 @@ > +Device-Tree bindings for i2c gpio based bus arbitrator > + > +bus-arbitration-gpios : > + Two GPIOs to use with the GPIO-based bus arbitration protocol > +(see below). > +The first should be an output, and is used to claim the I2C bus, > +the second should be an input, and signals that the other side (Client) > +wants to claim the bus. This allows two masters to share the same I2C bus. I'm confused why this is even needed; the I2C protocol itself defines how multi-master is supposed to work, just using the regular SCL/SDA lines.