Re: multiple devices behind a cardbus bridge (adding magma pci

[David Brownell <david-b@pacbell.net>]

> > > But for hotplug PCI, you need a hotplug pci controller that handles the
> > > initialization of that pci tree (among other things).  For this device,
> > > does it have a controller that can be addressed to do these things?
> > 
> > What do you mean by "handles the initialization"?  A hot plug PCI
> > controller mainly gives control over power sequencing and isolation of
> > the PCI devices behind the controller from the rest of the PCI tree,
> > right?  I'd think that this product would have to provide the same
> > functionality.
> 
> Yes, you are correct.  That's what I was trying to say.

Not all PCI bridges have per-slot power control over devices
connected to them though, do they?

I was under the strong impression that most didn't, and that
CompactPCI/HotplugPCI/Cardbus/... were the exceptions
to the rule.  And that these Magma extenders were likely
pretty standard -- the pictures I saw didn't show any of the
special hardware I've seen on HotplugPCI rackmounts, etc.

I guess it all comes down to needing more info about the Magma
card.  Also a potential confusion about what "Hotplug" means;
at one level it's a particular implementation of power switching
on PCI (CompactPCI and Cardbus being others), and at another
level it's a generic feature of the Linux PCI support that fires
automatically for all correctly configured devices (assuming it's
been configured in).

- Dave



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