linux-kernel - Re: [PATCH, RFC] Earlier I2C initialization

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Message-ID: <20080611111415.2a677a10@hyperion.delvare>
Date:	Wed, 11 Jun 2008 11:14:15 +0200
From:	Jean Delvare <khali@...ux-fr.org>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	David Brownell <david-b@...bell.net>,
	Ryan Mallon <ryan@...ewatersys.com>,
	Uli Luckas <u.luckas@...d.de>, i2c@...sensors.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH, RFC] Earlier I2C initialization

Hi Russell,

On Wed, 11 Jun 2008 10:00:16 +0100, Russell King - ARM Linux wrote:
> On Wed, Jun 11, 2008 at 10:11:30AM +0200, Jean Delvare wrote:
> > Hi David,
> > 
> > On Tue, 10 Jun 2008 13:55:07 -0700, David Brownell wrote:
> > > > Why don't you simply initialize the drivers in question with
> > > > subsys_initcall()? That's what i2c-pnx, i2c-omap, i2c-davinci and
> > > > tps65010 are doing at the moment.
> > > 
> > > If they happen to sit outside the I2C tree and *before* it in
> > > link order, things will misbehave.
> > 
> > Well, i2c system bus drivers shouldn't sit outside of the I2C tree, so
> > that's not a problem. If you start accepting that drivers live at
> > random places in the source tree, then there's simply no way to get
> > things right.
> 
> That's simply not a realistic view.  As I've already pointed out,
> framebuffer devices have I2C busses for reading the DDC information
> from monitors.  These I2C bus drivers live in drivers/video.
> 
> Video grabbers have I2C busses for controlling, eg, tuners and video
> decoders.  These live in drivers/media.
> 
> If I follow your argument, would you like cyber2000fb.c to be moved
> entirely from drivers/video into drivers/i2c/busses because it contains
> an i2c bus driver?  Clearly not.

Please read what I wrote again. I said: I2C SYSTEM BUS drivers should
live under drivers/i2c. DDC channels on graphics adapters and I2C buses
on multimedia adapters definitely do not qualify as system buses (and
don't need to be initialized early, either.)

Thanks,
-- 
Jean Delvare
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