linux-kernel - Re: [PATCH] i2c: Raise SDA for each received bit, if necessary

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Message-ID: <20160512090544.GB1638@katana>
Date:	Thu, 12 May 2016 11:05:44 +0200
From:	Wolfram Sang <wsa@...-dreams.de>
To:	Thomas Zimmermann <tdz@...rs.sourceforge.net>
Cc:	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] i2c: Raise SDA for each received bit, if necessary

Hi Thomas,

On Wed, Apr 27, 2016 at 08:11:54PM +0200, Thomas Zimmermann wrote:
> Some I2C adapters don't raise SDA by themselves when sending a bit. This
> behavior can be seen with the DDC channel of SiS 300 graphics cards.

I think you mean 'clients' or 'devices' here, not adapters (masters),
right? So, it seems you have a bus without a pull-up resistor (or a
broken one?) but use now a push-pull design. This is against the I2C
standard and for most circiuts quite dangerous as it can lead to
shortcuts.

Do you have any hints that the bus is designed this way? In which driver
do you want to use the new flag?

Thanks,

   Wolfram

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