PCI-PCI Bridge specs problem...

["Sushant S Ranade" <sushantsr@myw.ltindia.com>]

** Proprietary **

Hi PCI Developers,

I need u'r help in understanding PCI-PCI Bridge Specs.
I think there is one problem in the Specs 1.1 for PCI-PCI Bridge.
Page No 16, 2.2 Capabilities Not Supported, 1.3 point,
"Two bridges where the primary interface of one bridge is connected to
the secondary interface of the other and vice versa"

here we can interpret this statement in two ways, one for normal
cascading (considreing downstreem bridge) and second, where two buses,
two bridges with their interfaces reversed.
Now the first one is normal case, and same spacs says else whaere that
it supports it, where as the second one is the actual wrong condition.

Cascade:
		   #1	  	   #2
		   |   --------	   |   --------
	 ------	   |  | PPB#1  |   |  | PPB#2  |
	| Host |   +--+ Bridge +---+--+ Bridge +---
	|Bridge|---+ p|________|s  | p|________|s
	|______|   |  	           |
		   |	           |
			           |
	this is a comman way to put more buses. if u consider the PPB#2 then it satisfyes the statement.

LoopBack:
		   #1	  	     #2
		   |     --------    |
	 ------	   |    | PPB#1  |   |
	| Host |   +----+ Bridge +---+
	|Bridge|---+   p|________|s  |
	|______|   |    	     |
		   |     --------    |
		   |    | PPB#2  |   |
		   + -  + Bridge +---+
		   |   s|________|p  |
				     |
	this is not a comman way to connect PPBs. if u consider the PPB#2 then it satisfyes the statement.

this means, PCI-PCI Bridge Specs 1.1 is not clear for its meaning.....

or is there anything that i am missing?

thanking in anticipation,

--sushant