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Message-ID: <48344B02.7070308@scram.de>
Date: Wed, 21 May 2008 18:17:06 +0200
From: Jochen Friedrich <jochen@scram.de>
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To: Scott Wood <scottwood@freescale.com>
CC: Anton Vorontsov <avorontsov@ru.mvista.com>,
       linuxppc-dev list <linuxppc-dev@ozlabs.org>,
       "Kernel, Linux" <linux-kernel@vger.kernel.org>,
       Kumar Gala <galak@kernel.crashing.org>, Linux I2C <i2c@lm-sensors.org>,
       Jean Delvare <khali@linux-fr.org>, Paul Mackerras <paulus@samba.org>,
       Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] [POWERPC] Add i2c pins to dts and board setup
References: <4833FA0C.5090800@scram.de> <20080521151003.GA13858@ld0162-tx32.am.freescale.net>
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Hi Scott,

>> +   - linux,i2c-index : Can be used to hard code an i2c bus number.
>> +   - linux,i2c-class : Can be used to override the i2c class.
>
> Why do we need this?

There are still a bunch of i2c drivers using the old API (mainly v4l and dvb stuff)
which are slowly being converted by their subsystem maintainers, though.

> It'd be better to just convert any needed old-style drivers than add this
> to the device tree.

Sure. That's why the parameters are only optional. Once all i2c drivers are
converted, these parameters won't be used anymore. Maybe they should be marked
as deprecated.

>> +   - bus-frequency : Can be used to set the i2c bus frequency. If unspecified,
>> +     a default frequency of 60kHz is being used.
> 
> clock-frequency is the standard name for such things.

I was just confused by the fact that unlike a serial port, i2c is a bus itself.

Thanks,
Jochen