cgd
Sat Nov 23 13:58:18 PST 1996
Update of /cvsroot/src/sys/dev/pci
In directory netbsd1:/var/slash-tmp/cvs-serv19541

Modified Files:
	pci.c pcivar.h 
Log Message:
Provide a routine so that ISA/EISA bridges can set up a callback so
that their child busses can be attached after the PCI bus
autoconfiguration for their parent bus is done.

This works because:
	(1) there can be at most one ISA/EISA bridge per PCI bus, and
	(2) any ISA/EISA bridges must be attached to primary PCI
	    busses (i.e. bus zero).
   
That boils down to: there can only be one of these outstanding
at a time, it is cleared when configuring PCI bus 0 before any
subdevices have been found, and it is run after all subdevices
of PCI bus 0 have been found.

This (or something like it) is needed because there are some (legacy)
PCI devices which can show up as ISA/EISA devices as well (the prime
example of which are VGA controllers).  If you attach ISA from a
PCI-ISA/EISA bridge, and the bridge is seen before the video board is,
the board can show up as an ISA device, and that can (bogusly)
complicate the PCI device's attach code, or make the PCI device not be
properly attached at all.

This could be done with machine-dependent code, but as more ports
add support for PCI (and PCI-ISA/EISA bridges) more will need it.
The i386 port could (perhaps should) be converted to use it as well.