Intel 41210 - page 33

Intel® 41210 Serial to Parallel PCI Bridge Developer’s Manual 33
PCI-X Interface
•Target Terminations Initiated by the 41210
The 41210 responds with a retry to PCI-X when one of the following conditions is met:
— A memory read transaction occurs and the 41210 delayed transaction queue is full.
— A LOCK transaction is established from PCI Express*-to-PCI.
— A memory write transaction occurs and the 41210 has no free buffer space to accept the
write.
— A mem ory write is from a master other than the master that was p reviously retried
(starvation prevention mechanism).
Note: The 41210 never retries a completion since it always has enough buffer space for all split requests
it sends out. No transaction information is retained on any writes.
•Disconnect
The 41210 disconnects a transaction on PCI-X when one of the following conditions is met:
— The 41210 cannot accept any more write data and an ADB is reached.
— A split completion packet being sent, ADB is reached, and the 41210 read buffers are
running dry.
— Inverse decode window ends, and an upstream write is in progress, irrespective of the
availability of the write-buffer.
•Targe t Ab or t
The 41210 returns a target abort to PCI-X when one of the following conditions is met:
— The initial request received a target-abort on the peer PCI bus or a Completion with
Completer Abort status on the PCI Express* interface.
— All requests with address parity error and the parity error response bit is set.
•Master Abort
— The 41210 master aborts all memory transactions on PCI-X when the bus master enable
(BME) bit is cleared.
— Th e 41210 returns a master abort respons e in a split completion when the split cycle
master aborted on PCI Express*/peer PCI.
•Split Response
All memory read cycles that cross the 41210 receive this termination, if they are not retried.