RE: PCI-PCI Bridge specs problem...

["Olaf Birkeland" <olaf@interagon.com>]

Hi,

I interpret this:
"Two bridges where the primary interface of one bridge is connected to the
secondary interface of the other AND vice versa" (my capitalization)

as disallowing creating a loop with PPB1-PRI connected to PPB2-SEC when at
the same time PPB1-SEC is connected to PPB2-PRI. Thus the normal cascade
conncetion is not prohibited by this statement.

Regards,
- Olaf Birkeland

> -----Original Message-----
> From: Sushant S Ranade [mailto:sushantsr@myw.ltindia.com]
> Sent: September 19, 2002 14:41
> To: pci-sig@znyx.com
> Subject: PCI-PCI Bridge specs problem...
>
>
> ** 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
>
>
>
>
>