linux-kernel - Re: [PATCH 10/10] i2c: pca954x: get rid of the i2c deadlock workaround

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Date:	Mon, 04 Jan 2016 16:45:36 +0100
From:	Peter Rosin <peda@...ator.liu.se>
To:	Lars-Peter Clausen <lars@...afoo.de>,
	Wolfram Sang <wsa@...-dreams.de>
CC:	Peter Rosin <peda@...ntia.se>, Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Peter Korsgaard <peter.korsgaard@...co.com>,
	Guenter Roeck <linux@...ck-us.net>, linux-i2c@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 10/10] i2c: pca954x: get rid of the i2c deadlock workaround

On 2016-01-04 16:19, Lars-Peter Clausen wrote:
> On 01/04/2016 04:10 PM, Peter Rosin wrote:
>> From: Peter Rosin <peda@...ntia.se>
>>
>> Signed-off-by: Peter Rosin <peda@...ntia.se>
> 
> It would be quite good if the commit messaged said why it is now safe to
> remove the workaround.

Right, hmm, the two last patches seemed obvious at the time I wrote them,
but now I see a problem.

E.g. if two pca954x devices that depends on being idle when client devices
are not accessed happen to sit on the same bus (perhaps because the muxes
are used to hide a bunch of identical devices), it is indeed not safe to
make this change.

Thanks for making my think, and consider 9/10 and 10/10 dropped.

Cheers,
Peter
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