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

Started byWolfram Sang <wsa@the-dreams.de>
First post2015-09-11 21:00 +0200
Last post2015-09-14 07:10 +0200
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  Re: [PATCH-v5 RESEND 2/5] i2c: pxa: enable/disable i2c module across  msg xfer Wolfram Sang <wsa@the-dreams.de> - 2015-09-11 21:00 +0200
    Re: [PATCH-v5 RESEND 2/5] i2c: pxa: enable/disable i2c module across  msg xfer Vaibhav Hiremath <vaibhav.hiremath@linaro.org> - 2015-09-14 07:10 +0200

#1223041 — Re: [PATCH-v5 RESEND 2/5] i2c: pxa: enable/disable i2c module across msg xfer

FromWolfram Sang <wsa@the-dreams.de>
Date2015-09-11 21:00 +0200
SubjectRe: [PATCH-v5 RESEND 2/5] i2c: pxa: enable/disable i2c module across msg xfer
Message-ID<q7BId-1Oi-3@gated-at.bofh.it>

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On Mon, Aug 24, 2015 at 11:29:35AM +0530, Vaibhav Hiremath wrote:
> From: Yi Zhang <yizhang@marvell.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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#1223834

FromVaibhav Hiremath <vaibhav.hiremath@linaro.org>
Date2015-09-14 07:10 +0200
Message-ID<q8ubD-4LN-1@gated-at.bofh.it>
In reply to#1223041

On Saturday 12 September 2015 12:23 AM, Wolfram Sang wrote:
> On Mon, Aug 24, 2015 at 11:29:35AM +0530, Vaibhav Hiremath wrote:
>> From: Yi Zhang <yizhang@marvell.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.
>

Hmm, Ok.
Not sure what else I can bring up here.

> Can't you use Runtime PM for that?
>

I haven't tried it though, I can give a try and check.

Thanks,
Vaibhav

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