Envelope-to: linux-kernel@vger.kernel.org
Date: Wed, 28 Apr 2004 10:13:57 +0200
From: stefan.eletzhofer@eletztrick.de
To: Greg KH <greg@kroah.com>, stefan.eletzhofer@eletztrick.de,
       linux-kernel@vger.kernel.org
Subject: Re: i2c_get_client() missing?
Message-ID: <20040428081357.GA11274@gonzo.local>
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	Greg KH <greg@kroah.com>, linux-kernel@vger.kernel.org
References: <20040427150144.GA2517@gonzo.local> <20040427153512.GA19633@kroah.com> <20040427192119.A21965@flint.arm.linux.org.uk>
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On Tue, Apr 27, 2004 at 07:21:19PM +0100, Russell King wrote:
> On Tue, Apr 27, 2004 at 08:35:12AM -0700, Greg KH wrote:
> > Where do you need to access it from?  Why do all of the current drivers
> > not need it?
> 
> The "traditional Linux" i2c model is one where the i2c bus is local to
> the card, so the overall driver knows where the bus is, and what devices
> to expect, and it's all nicely encapsulated.
> 
> The variant on that is the i2c sensor stuff, where the individual i2c
> bus device drivers export data to userspace themselves.
> 
> However, there's another class, where the i2c bus contains things like
> RTC and system control stuff, which can be found on embedded devices.
> Such an i2c bus is often shared between multiple parts of the system,
> and lumping them all together into one massive driver does not make
> sense.

Thats exactly what I tried to say with my other post. Thanks for spelling
it more precisely.

> 
> For instance, one platform I have here has an i2c bus with a RTC on,
> and optionally a couple of EEPROMs giving the dimentions of the memory
> on a couple of expansion boards.  It doesn't make sense to lump the
> RTC code along side the memory controller configuration code, along
> with the i2c bus driver.

Again, exatly what I thought when I split up I2C RTC chip access and
higher level RTC device handling stuff.

> 
> I2C is much much more than sensors and graphics capture chips.

Definitely.

> -- 
> Russell King
>  Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
>  maintainer of:  2.6 PCMCIA      - http://pcmcia.arm.linux.org.uk/
>                  2.6 Serial core
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-- 
Eletztrick Computing - Customized Linux Development
Stefan Eletzhofer, Marktstrasse 43, DE-88214 Ravensburg
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