PI7C8140AMAE Pericom Semiconductor, PI7C8140AMAE Datasheet - Page 40

• Manufacturer Part Number: PI7C8140AMAE
• Description: IC PCI-PCI BRIDGE 2PORT 128-QFP
• Manufacturer: Pericom Semiconductor

Specifications of PI7C8140AMAE

• Applications: *
• Interface: *
• Voltage - Supply: *
• Package / Case: 128-QFP
• Mounting Type: Surface Mount
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: 0 C
• Mounting Style: SMD/SMT
• Operating Supply Voltage: 3 V to 3.6 V
• Supply Current (max): 230 mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

07-0067
Table 4-1. Summary of Transaction Ordering
Note: The superscript accompanying some of the table entries refers to any applicable ordering rule
listed in this section. Many entries are not governed by these ordering rules; therefore, the
implementation can choose whether or not the transactions pass each other.
The entries without superscripts reflect the bridge’s implementation choices.
The following ordering rules describe the transaction relationships. Each ordering rule is followed by an
explanation, and the ordering rules are referred to by number in Table 4-1. These ordering rules apply to
posted write transactions, delayed write and read requests, and delayed write and read completion
transactions crossing the bridge in the same direction. Note that delayed completion transactions cross
the bridge in the direction opposite that of the corresponding delayed requests.
1. Posted write transactions must complete on the target bus in the order in which they were received
on the initiator bus. The subsequent posted write transaction can be setting a flag that covers the data in
the first posted write transaction; if the second transaction were to complete before the first transaction,
a device checking the flag could subsequently consume stale data.
2. A delayed read request traveling in the same direction as a previously queued posted write
transaction must push the posted write data ahead of it. The posted write transaction must complete on
the target bus before the delayed read request can be attempted on the target bus. The read transaction
can be to the same location as the write data, so if the read transaction were to pass the write
transaction, it would return stale data.
3. A delayed read completion must ‘‘pull’’ ahead of previously queued posted write data traveling in
the same direction. In this case, the read data is traveling in the same direction as the write data, and the
initiator of the read transaction is on the same side of the bridge as the target of the write transaction.
The posted write transaction must complete to the target before the read data is returned to the initiator.
The read transaction can be a reading to a status register of the initiator of the posted write data and
therefore should not complete until the write transaction is complete.
4. Delayed write requests cannot pass previously queued posted write data. For posted memory write
transactions, the delayed write transaction can set a flag that covers the data in the posted write
transaction. If the delayed write request were to complete before the earlier posted write transaction, a
device checking the flag could subsequently consume stale data.
5. Posted write transactions must be given opportunities to pass delayed read and write requests and
completions. Otherwise, deadlocks may occur when some bridges which support delayed transactions
and other bridges which do not support delayed transactions are being used in the same system. A
fairness algorithm is used to arbitrate between the posted write queue and the delayed transaction
queue.
Pass
Posted Write
Delayed Read Request
Delayed Write Request
Delayed Read
Completion
Delayed Write
Completion
Posted Write
No
No
No
No
Yes
1
2
4
3
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Delayed Read
Request
Yes
Yes
Yes
Yes
Yes
5
Delayed Write
Request
Yes
Yes
Yes
Yes
Yes
5
2-PORT PCI-TO-PCI BRIDGE
March 20, 2007 – Revision 1.01
Delayed Read
Completion
Yes
Yes
Yes
Yes
Yes
5
Delayed Write
Completion
Yes
Yes
Yes
Yes
Yes
PI7C8140A
5