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From: David Brownell <david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>
To: Ryan Mallon <ryan-7Wk5F4Od5/oYd5yxfr4S2w@public.gmane.org>
Cc: Uli Luckas <u.luckas-vFjI0mZ6VZs@public.gmane.org>,
	Russell King - ARM Linux
	<linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>,
	i2c-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org
Subject: Re: Earlier I2C initialization
Date: Mon, 9 Jun 2008 13:59:12 -0700	[thread overview]
Message-ID: <200806091359.12791.david-b@pacbell.net> (raw)
In-Reply-To: <484D947D.1090900-7Wk5F4Od5/oYd5yxfr4S2w@public.gmane.org>

On Monday 09 June 2008, Ryan Mallon wrote:
> > 
> > Talk to i2c and framebuffer people about changing the link order.
> > 
> > i2c should really be initialised before framebuffer devices because
> > framebuffer devices tend to want to read DDC from monitors, which is
> > basically a I2C EEPROM in the monitor.
> > 
> > ... but there's probably some reason why it's done the way it is today,
> > and changing it could well cause stuff to break.
> 
> We have made i2c the first driver subsystem to come up in our 2.6.20
> kernel since we use i2c io expanders for power domain control. All we
> did was change drivers/Makefile so that obj-$(CONFIG_I2C) += i2c/ is at
> the very top of the file. We didn't have any problems with doing this.
> YMMV of course.

OMAP does much the same thing, for the same reason, and the I2C
adapter gets initialized earlier too (so power management chips
will be fully usable before driver_initcall code runs).

Unless there's a downside on x86, I'd just suggest someone submit
a patch moving I2C init "early" so it merges in 2.6.27 ... cc to
LKML to scare out more potential problems, but I have a hard time
imagining there'd really be any.

- Dave


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       reply	other threads:[~2008-06-09 20:59 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <200806091541.43899.u.luckas@road.de>
     [not found] ` <20080609135739.GE30971@flint.arm.linux.org.uk>
     [not found]   ` <484D947D.1090900@bluewatersys.com>
     [not found]     ` <484D947D.1090900-7Wk5F4Od5/oYd5yxfr4S2w@public.gmane.org>
2008-06-09 20:59       ` David Brownell [this message]
     [not found]         ` <200806091359.12791.david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>
2008-06-09 21:27           ` [PATCH, RFC] Earlier I2C initialization Ryan Mallon
2008-06-10  6:57             ` Jean Delvare
2008-06-10 20:55               ` David Brownell
     [not found]                 ` <200806101355.07792.david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>
2008-06-11  8:11                   ` Jean Delvare
2008-06-11  9:00                     ` Russell King - ARM Linux
     [not found]                       ` <20080611090016.GA5338-f404yB8NqCZvn6HldHNs0ANdhmdF6hFW@public.gmane.org>
2008-06-11  9:14                         ` Jean Delvare
     [not found]                     ` <48503432.6010105@bluewatersys.com>
     [not found]                       ` <48503432.6010105-7Wk5F4Od5/oYd5yxfr4S2w@public.gmane.org>
2008-06-11 12:05                         ` Jean Delvare
2008-06-11 18:31                     ` David Brownell
2008-06-12 18:44                       ` Jean Delvare
2008-06-12 19:57                         ` David Brownell
2008-06-24 17:06                           ` Jean Delvare
     [not found]                     ` <20080611101130.1a667abe-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
2008-06-11 20:23                       ` Ryan Mallon
2008-06-10 21:33               ` Ryan Mallon
2008-06-10  9:46                 ` Uli Luckas
2008-06-11  3:12               ` Ryan Mallon
2008-06-11  7:40                 ` Jean Delvare
     [not found]                   ` <485031D5.3020606@bluewatersys.com>
     [not found]                     ` <485031D5.3020606-7Wk5F4Od5/oYd5yxfr4S2w@public.gmane.org>
2008-06-11 12:18                       ` Jean Delvare
2008-06-11 20:27                         ` David Brownell
2008-06-11 20:54                           ` Jean Delvare
2008-06-11 21:24                             ` Ryan Mallon
     [not found]                               ` <485042A6.3030705-7Wk5F4Od5/oYd5yxfr4S2w@public.gmane.org>
2008-06-24 16:39                                 ` Jean Delvare
2008-06-26 21:12                                   ` Ryan Mallon
2008-06-27 10:41                                     ` Jean Delvare
2008-06-29 20:34                                       ` Ryan Mallon
2008-06-11 21:31                             ` Maciej W. Rozycki
2008-06-12 20:21                               ` David Brownell
     [not found]                   ` <20080611094039.287ac136-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
2008-06-11 20:13                     ` Ryan Mallon

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