From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Brownell Subject: Re: [PATCH, RFC] Earlier I2C initialization Date: Thu, 12 Jun 2008 13:21:03 -0700 Message-ID: <200806121321.03429.david-b@pacbell.net> References: <200806091541.43899.u.luckas@road.de> <20080611225416.169574a0@hyperion.delvare> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org To: "Maciej W. Rozycki" Cc: Jean Delvare , Ryan Mallon , Uli Luckas , Russell King - ARM Linux , i2c@lm-sensors.org, linux-kernel@vger.kernel.org List-Id: linux-i2c@vger.kernel.org On Wednesday 11 June 2008, Maciej W. Rozycki wrote: > > That being said, I'm not sure if the comparison with the PCI subsys= tem > > holds... I am under the impression that PCI bus handling doesn't > > require dedicated drivers? At least I can't see any under drivers/p= ci. >=20 > =A0Of course it does require them. =A0It is just due to their very na= ture they > tend to be placed under arch/, PCI root hubs, yes. The drivers/pci/hotplug bridges are slightly more generic, ditto drivers/pci/pcie and the CardBus bridges in drivers/pcmcia. At one point, lack of a generic (non-hotplug) PCI bridge driver was viewed as a weakness of that driver stack. Also, drivers/acpi/pci_root.c binds the root at subsys_initcall. That's done *after* some earlier PCI magic; I never bothered to sort through that little maze. > although there are some cases where the=20 > same system controller can be used for a range of processors (e.g. so= me > Marvell chips can be used either with MIPS or PowerPC CPUs) and they = might > be arguably put in a place more suitable for sharing between > architectures. =A0See arch/mips/pci/ for an example of a generous bun= ch of > PCI host drivers. Which, for the record, get very early initialization using two different mechanisms: - many use arch_initcall() - the "arch" subtree is linked before the "drivers" subtree I don't think I2C needs to worry about arch_initcall just now, but if necessary it could initialize earlier than subsys_initcall. - Dave