hotplugging a bridge?

[AMusingFool <clemmd@rpi.edu>]

Hi all,

I have a machine with a pci-pci bridge that gets configured incorrectly. 
It gets no memory of any sort allocated, and while the bridges behind it 
(pci-cardbus bridges, FWIW) are noted as being bridges, no devices on 
them are available. Right now it can be gotten to work by probing 
memory, and manually setting memory settings, but that's hardly elegant. 
Since changing the hardware is not an option, I was looking at 
simulating a hotplug event with it, to see if it would get allocated 
correctly at that point.

Now, I can't actually test it directly (at the moment; someone else is 
using it), so to try to test things out, I got a laptop, and was doing 
the same sort of testing with the laptop's pci-cardbus bridge. I found 
pci_device_restart(), and wrote a module to call that. It sort of works, 
in that memory does get reallocated; however, it no longer finds 
anything on that cardbus again. It doesn't generate hotplug events, and 
doesn't even do anything with a card left plugged in when the bridge is 
zapped.

I then tried linking in bits of the kernel (starting with 
pcibios_allocate_bus_resources(), and then moving on to its 
dependencies), but that's ending up being more of a kludge than the 
memory probe.

I also tried calling pci_scan_bus() afterwards, but that didn't seem to 
help... Maybe I need to call something else before calling that?

So, a couple of questions: first, can this be considered a bug that the 
kernel doesn't seem to recognize that the new device is a bridge? 
Second, am I just missing something somewhere? ie: does anyone have any 
suggestions for how to proceed? or even what to look for?

FWIW, I'm not using udev or devfs. I'm on kernel 2.4.22 (and moving 
beyond 2.4.x is also not an option).  I have not moved to the 2004-03-11 
hotplug package either, although I think that is an option, if you all 
think that might make a difference.

Thanks in advance for any help you can provide,

Dave Clemmer 




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