Altera Arria 10 Avalon-ST - Manual (Page 174)

Protocol Extensions Supported
The Transaction Layer supports the following protocol extensions:
• TLP Processing Hints (TPH)—Supports both a Requester and Completer. The Application Layer
should implement the TPH Requester Capabilities Structure using the soft logic in the Application
Layer Extended Configuration Space. The Transaction Layer supports both Protocol Hint (PH) bits
and Steering Tags (ST). The Transaction Layer does not support the optional Extended TPH TLP
prefix.
• Atomic Operations—Supports both Requester and Completer. The RX buffer supports two, four, or
eight non-posted data credits depending on the performance level you selected for the RX buffer
credit allocation—performance for received requests under the System Settings heading of the
parameter editor. The Transaction Layer also supports Atomic Operation Egress Blocking to prevent
forwarding of AtomicOp Requests to components that should not receive them.
• ID-Based Ordering (IDO)—The Transaction Layer supports ID-Based Ordering to permit certain
ordering restrictions to be relaxed to improve performance. However, the Transaction Layer does
reorder the TLPs. On the RX side, ID-Based reordering should be implemented in soft logic. On the
TX side, the Application Layer should set the IDO bit, which is bit 8 the
Device Control Register
2
, in the TLPs that it generates.
Data Link Layer
The Data Link Layer is located between the Transaction Layer and the Physical Layer. It maintains packet
integrity and communicates (by DLL packet transmission) at the PCI Express link level (as opposed to
component communication by TLP transmission in the interconnect fabric).
The DLL implements the following functions:
• Link management through the reception and transmission of DLL packets (DLLP), which are used for
the following functions:
• Power management of DLLP reception and transmission
• To transmit and receive
ACK
/
NACK
packets
• Data integrity through generation and checking of CRCs for TLPs and DLLPs
• TLP retransmission in case of
NAK
DLLP reception using the retry buffer
• Management of the retry buffer
• Link retraining requests in case of error through the Link Training and Status State Machine
(LTSSM) of the Physical Layer
11-10 Protocol Extensions Supported
UG-01145_avst
2014.08.18
Altera Corporation IP Core Architecture
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