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From: Benjamin Herrenschmidt <bh40@calva.net>
To: Ivan Kokshaysky <ink@jurassic.park.msu.ru>, <linux-kernel@vger.kernel.org>
Subject: Re: PCI bridge setup weirdness
Date: Fri, 8 Dec 2000 15:31:08 +0100
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>
>No, pci_read_bridge_bases() is obsoleted by new pci setup code. ;-)
>You have to set up bus resources properly in pcibios_fixup_bus().
>For a single root bus configuration, you don't need to do anything
>with the root bus itself - its resources already point to ioport_resource
>and iomem_resource, which should be ok. For pci-pci bridges you have
>to add something like this:

The problem I have (and this is why I don't setup host resources
properly on multi-host PPCs yet) is that some hosts can have several
non-contiguous ranges (especially with memory, IO is usually a single
contiguous range).

There are simply not enough resource "slots" in the current structures
to handle all possibles cases.

They basically have a host bridge register in which each low bit enables
decoding of a 256Mb region in the range 0xn0000000 and each high bit
enable decoding of a 16Mb region in the range 0xFn000000

The typical setup is to have one (or more) 256Mb regions, and one 16Mb
region, but that can change from model to model.

Ben

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