From: Mark Brown <broonie@opensource.wolfsonmicro.com>
To: Stephen Warren <swarren@wwwdotorg.org>
Cc: Naveen Krishna Chatradhi <ch.naveen@samsung.com>,
linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-samsung-soc@vger.kernel.org, grundler@chromium.org,
devicetree-discuss@lists.ozlabs.org, 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
Date: Sat, 15 Dec 2012 23:21:36 +0900 [thread overview]
Message-ID: <20121215142135.GB22033@opensource.wolfsonmicro.com> (raw)
In-Reply-To: <50CB4E99.9060506@wwwdotorg.org>
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On Fri, Dec 14, 2012 at 09:06:49AM -0700, Stephen Warren wrote:
> On 12/13/2012 10:50 PM, Naveen Krishna Chatradhi wrote:
> > +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.
Practically speaking essentially no systems actually do that - mostly
Linux will treat failure to get the bus as an error for example. You
also get things like read operations which appear as multiple
transactions on the I2C bus so require something higher level than what
multi-master provides.
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next prev parent reply other threads:[~2012-12-15 14:21 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-14 5:50 [PATCH 0/2] i2c: Implement generic gpio based bus arbitration Naveen Krishna Chatradhi
[not found] ` <1355464254-12768-1-git-send-email-ch.naveen-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
2012-12-14 5:50 ` [PATCH 1/2] i2c-core: Add gpio based bus arbitration implementation Naveen Krishna Chatradhi
2012-12-14 16:06 ` Stephen Warren
2012-12-15 14:21 ` Mark Brown [this message]
[not found] ` <20121215142135.GB22033-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org>
2013-01-24 11:13 ` Wolfram Sang
[not found] ` <20130124111329.GC12933-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2013-01-24 11:18 ` Mark Brown
[not found] ` <20130124111845.GO4955-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org>
2013-01-24 11:39 ` Wolfram Sang
[not found] ` <20130124113948.GD12933-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2013-01-26 5:00 ` Mark Brown
[not found] ` <1355464254-12768-2-git-send-email-ch.naveen-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
2012-12-19 12:32 ` Grant Likely
2012-12-19 17:14 ` Mark Brown
2012-12-20 0:17 ` Simon Glass
[not found] ` <CAPnjgZ30MQS1OT3GOFLG9HntoD8NrzNw6bB_d1fiJEgHcMDGUA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-12-20 0:58 ` Grant Likely
[not found] ` <20121219171423.GW4985-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org>
2012-12-20 0:53 ` Grant Likely
2012-12-14 5:50 ` [PATCH 2/2] i2c-s3c2410: Add GPIO based bus arbitration functionality Naveen Krishna Chatradhi
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