Forcing PCI-PCI bridge to have memory resources

[Bret Indrelee]

I'm working with Linux version 2.4.18-xfs with hotswap support.

I'm trying to make a PCI-PCI bridge always have a minimum of 1MB of
memory address space allocated to it. I know that the BIOS we are
using always (correctly, by spec) sets a bridge with no devices behind 
it to disable the memory window. It does this by setting the 
MEM_LIMIT < MEM_BASE.

I've been going through the sources in drivers/pci, trying to figure
out how things are set up. At the time of the pci scan, the resources
are usually initialized (in bci_read_breidge_bases) by doing a read of 
the bridge registers and setting the resource values appropropriately.

For the disabled bridges, the resources are copied from the parent
which in this case results in 0 being set in flags, start and end.

It looks like I will want to call pci_assign_resource(dev, 1); in
order to give it a memory window, but I'm not sure how to initialize
the resources so they are assigned correctly.

Our situation is similiar to what a hotswap CPCI system should encounter
when a hotswap device is inserted behind a previously empty PCI-PCI bridge.

Any help people can give would be greatly appreciated.

-Bret

-- 
Bret Indrelee                 QLogic Corporation
[e-mail]      6321 Bury Driver, St 13, Eden Prairie, MN 55346