82870P2P64H2 Datasheet, PDF (118/217 Pages) –

Functional Description
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4.1.7 Transaction Termination
Normal Master Termination
As a PCI master, the P64H2 uses normal termination if PxDEVSEL# is returned by the target
within five clock cycles of PxFRAME# assertion. It terminates a transaction when the following
conditions are met:
• All write data for the transaction is transferred from the P64H2 data buffers to the target.
• The master latency timer expires and the P64H2’s bus grant is de-asserted.
Master Abort Termination
If a P64H2-initiated transaction is not responded to with PxDEVSEL# within five clocks of
PxFRAME# assertion, the P64H2 terminates the transaction with a master abort. The P64H2 sets
the received master abort bit in the status register corresponding to the target bus.
Note: When the P64H2 performs a Type 1 to special cycle translation, a master abort is the expected
termination for the special cycle on the target bus. In this case, the master abort received bit is not
set, and the Type 1 con-figuration transaction is disconnected after the first data phase.
Target Termination Received by the Intel^® P64H2
When the P64H2 receives a retry or disconnect response from a target, it will re-initiate the
transfer with the remaining length. If the P64H2 receives a target abort, and the cycle requires
completion on the hub interface, the P64H2 will return the target abort code to the hub interface as
the completion status.
Target Termination Initiated by the Intel^® P64H2
The P64H2 returns a target retry to an initiator for memory read transactions when any of the
following conditions is met:
• A new transaction for delayed transaction queue.
• The request has already been queued, but has not completed on the hub interface.
• The delayed transaction queue is full, and the transaction cannot be queued.
• A LOCK transaction has been established from the hub interface to PCI.
The P64H2 disconnects an initiator when one of the following conditions is met:
• The P64H2 cannot accept any more write data
• The P64H2 has no more read data to deliver
• If the memory address is non-linear
The P64H2 returns a target abort to PCI when the cycle master aborted or target aborted on the
hub interface.
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Intel^® 82870P2 P64H2 Datasheet