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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 12:39:48 +0100	[thread overview]
Message-ID: <20130124113948.GD12933@pengutronix.de> (raw)
In-Reply-To: <20130124111845.GO4955@opensource.wolfsonmicro.com>

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On Thu, Jan 24, 2013 at 07:18:47PM +0800, Mark Brown wrote:
> On Thu, Jan 24, 2013 at 12:13:29PM +0100, Wolfram Sang wrote:
> > On Sat, Dec 15, 2012 at 11:21:36PM +0900, Mark Brown wrote:
> 
> > > 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?
> 
> A read is typically implemented as a write of the register address
> followed by a read of the value, usually with the ability to free the
> bus in between.  If two devices attempt to access the register map
> simultaneously this results in the address going wrong.

Could happen. But in what situations will one not use repeated start
here? Especially when designing a multi-master bus?

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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  reply	other threads:[~2013-01-24 11:40 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
2013-01-24 11:18         ` Mark Brown
2013-01-24 11:39           ` Wolfram Sang [this message]
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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