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From: Mark Brown <broonie-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org>
To: Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
Cc: Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>,
	Naveen Krishna Chatradhi
	<ch.naveen-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>,
	linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-samsung-soc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	grundler-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org,
	devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org,
	ben-linux-elnMNo+KYs3YtjvyW6yDsg@public.gmane.org,
	khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org,
	naveen-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org
Subject: Re: [PATCH 1/2] i2c-core: Add gpio based bus arbitration implementation
Date: Sat, 26 Jan 2013 13:00:06 +0800	[thread overview]
Message-ID: <20130126050004.GC10580@opensource.wolfsonmicro.com> (raw)
In-Reply-To: <20130124113948.GD12933-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>

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On Thu, Jan 24, 2013 at 12:39:48PM +0100, Wolfram Sang wrote:
> On Thu, Jan 24, 2013 at 07:18:47PM +0800, Mark Brown wrote:

> > 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?

Well, you're depending on the specific drivers doing things that way and
it's actually quite rare for the controller drivers in Linux to support
I2C_M_NOSTART which discourages this.

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  parent reply	other threads:[~2013-01-26  5:00 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
     [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 [this message]
     [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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