Messages in this thread | | | From | David Brownell <> | Subject | Re: [PATCH, RFC] Earlier I2C initialization | Date | Thu, 12 Jun 2008 13:21:03 -0700 |
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On Wednesday 11 June 2008, Maciej W. Rozycki wrote: > > That being said, I'm not sure if the comparison with the PCI subsystem > > holds... I am under the impression that PCI bus handling doesn't > > require dedicated drivers? At least I can't see any under drivers/pci. > > Of course it does require them. It is just due to their very nature 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 > same system controller can be used for a range of processors (e.g. some > 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. See arch/mips/pci/ for an example of a generous bunch 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
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