RE: PCI2.2 Master Transaction Claiming

[Richard Walter <rwalter@brocade.com>]

Bert,

It's not a violation for a device to claim it's own transaction.  In fact, I
have vague memories of a device back around '95 (in the "olden times" :) )
that did this somewhat regularly.

However, I believe that there is an issue with a device sampling it's own
pins while it is driving them.  I recall there was some discussion about
this on the reflector a few years back (and it may only apply at 66Mhz) that
due to the reflected wave switching characteristics of PCI, a device may not
see a stable input when it is driving the I/O pin.  There was talk about
needing to put MUXs inside the device to cause the target to look at the
real pins when not the master and to look at internal nodes when it was the
master.

-Richard Walter
Senior Hardware Engineer
Brocade Communications Systems
rwalter@brocade.com
Note: I speak for myself, not for Brocade Communications.

-----Original Message-----
From: Bert Marston [mailto:bert@quadic.com]
Sent: Friday, June 29, 2001 10:52 AM
To: pci-sig@znyx.com
Subject: PCI2.2 Master Transaction Claiming


Does anyone know if it violates protocol for a PCI2.2 master to claim a
transaction that it generated?  Specifically, this can happen to a
bridge if the software programs it strangely.  Is it the bridge's
responsibility to check for this and not claim the transaction if it
knows that it is the source, allowing a master abort?

Thanks,
Bert Marston


--

Bert Marston                 phone: (207)773-2662 X3052
Quadic Systems, Inc            fax: (207)773-1550
39 Darling Avenue            email: bert@quadic.com
South Portland, ME 04106

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