From: Wolfram Sang <w.sang@pengutronix.de>
To: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Stephen Warren <swarren@wwwdotorg.org>,
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, 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: Thu, 24 Jan 2013 12:13:29 +0100 [thread overview]
Message-ID: <20130124111329.GC12933@pengutronix.de> (raw)
In-Reply-To: <20121215142135.GB22033@opensource.wolfsonmicro.com>
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Hi,
On Sat, Dec 15, 2012 at 11:21:36PM +0900, Mark Brown wrote:
> 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.
It is true that Linux currently does not have proper multi-master
support. It is worth a look what is missing and how far we can get with
the I2C specified arbitration IMO.
> 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.
I don't get what you mean here. Can you elaborate?
That being said. Grant's design was the most promising one.
Thanks,
Wolfram
--
Pengutronix e.K. | Wolfram Sang |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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next prev parent reply other threads:[~2013-01-24 11:13 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
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
2013-01-24 11:13 ` Wolfram Sang [this message]
2013-01-24 11:18 ` Mark Brown
2013-01-24 11:39 ` Wolfram Sang
2013-01-26 5:00 ` Mark Brown
2012-12-19 12:32 ` Grant Likely
2012-12-19 17:14 ` Mark Brown
2012-12-20 0:17 ` Simon Glass
2012-12-20 0:58 ` Grant Likely
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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