linux-kernel - Re: [PATCH-v5 RESEND 2/5] i2c: pxa: enable/disable i2c module across msg xfer

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Message-ID: <20150911185312.GA1516@katana>
Date:	Fri, 11 Sep 2015 20:53:12 +0200
From:	Wolfram Sang <wsa@...-dreams.de>
To:	Vaibhav Hiremath <vaibhav.hiremath@...aro.org>
Cc:	linux-arm-kernel@...ts.infradead.org, robh+dt@...nel.org,
	robert.jarzmik@...e.fr, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org,
	Yi Zhang <yizhang@...vell.com>
Subject: Re: [PATCH-v5 RESEND 2/5] i2c: pxa: enable/disable i2c module across
 msg xfer

On Mon, Aug 24, 2015 at 11:29:35AM +0530, Vaibhav Hiremath wrote:
> From: Yi Zhang <yizhang@...vell.com>
> 
> Enable i2c module/unit before transmission and disable when it
> finishes.
> 
> why?
> It's because the i2c bus may be disturbed if the slave device,
> typically a touch, powers on.

I am not convinced, "may disturb" is too weak for me. It would need a
way more detailed description of the problem which makes clear that
this mechanism is the only way to go forward.

Can't you use Runtime PM for that?


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