linux-kernel - Re: [PATCH] drivers: i2c: i2c-st: Update i2c timings

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Date:	Mon, 21 Jul 2014 16:03:10 +0200
From:	Wolfram Sang <wsa@...-dreams.de>
To:	Maxime Coquelin <maxime.coquelin@...com>
Cc:	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
	Srinivas Kandagatla <srinivas.kandagatla@...il.com>,
	Patrice Chotard <patrice.chotard@...com>, kernel@...inux.com
Subject: Re: [PATCH] drivers: i2c: i2c-st: Update i2c timings

> Sorry for the late reply, but it took time to get the answer.

No problem, thanks for keeping at it.

> > Which also came from the HW guys? Please ask for details why 10%, too.
> 
> This is a safety margin.

I understood that. Still why 10%? Is it randomly guessed? Was 5% the
first working value, so we took this * 2? Is it a secret value from a
well-experienced engineer? While not perfect, I'd accept those reasons
as long as they are clearly stated. I just want to avoid trial and error
trying to find a good value.

> Note that the I2C specification only defines minimal timings.
> 
> Is it fine for you?
> Can I re-send a v2, which:
>  - Indicate the Toshiba TV is one of the affected devices in the commit message
>  - Indicate the 10% margin is a safety one in the commit message
>  - Add a comment above the table indicating these are standard timings + 10% margin.

Basically yes. The same information should be in the commit message and
the comment above the table. I'd really like a short reason why 10%.

Regards,

    Wolfram

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