1. Datasheet 2. Getting Started with the Arria V Hard IP for PCI Express 3. Parameter Settings 4. Interfaces and Signal Descriptions 5. Registers 6. Interrupts 7. Error Handling 8. IP Core Architecture 9. Transaction Layer Protocol (TLP) Details 10. Throughput Optimization 11. Design Implementation 12. Additional Features 13. Hard IP Reconfiguration 14. Transceiver PHY IP Reconfiguration 15. Testbench and Design Example 16. Debugging A. Transaction Layer Packet (TLP) Header Formats B. Lane Initialization and Reversal C. Document Revision History
1.1. Arria V Avalon-ST Interface for PCIe Datasheet 1.2. Features 1.3. Release Information 1.4. Device Family Support 1.5. Configurations 1.6. Example Designs 1.7. Debug Features 1.8. IP Core Verification 1.9. Performance and Resource Utilization 1.10. Recommended Speed Grades 1.11. Creating a Design for PCI Express
4.1. Arria V Hard IP for PCI Express with Avalon-ST Interface to the Application Layer 4.2. Clock Signals 4.3. Reset Signals 4.4. Hard IP Status 4.5. Error Signals 4.6. ECRC Forwarding 4.7. Interrupts for Endpoints 4.8. Interrupts for Root Ports 4.9. Completion Side Band Signals 4.10. Transaction Layer Configuration Space Signals 4.11. LMI Signals 4.12. Power Management Signals 4.13. Physical Layer Interface Signals
5.1. Correspondence between Configuration Space Registers and the PCIe Specification 5.2. Type 0 Configuration Space Registers 5.3. Type 1 Configuration Space Registers 5.4. PCI Express Capability Structures 5.5. Intel-Defined VSEC Registers 5.6. CvP Registers 5.7. Uncorrectable Internal Error Mask Register 5.8. Uncorrectable Internal Error Status Register 5.9. Correctable Internal Error Mask Register 5.10. Correctable Internal Error Status Register
15.6.1. ebfm_barwr Procedure 15.6.2. ebfm_barwr_imm Procedure 15.6.3. ebfm_barrd_wait Procedure 15.6.4. ebfm_barrd_nowt Procedure 15.6.5. ebfm_cfgwr_imm_wait Procedure 15.6.6. ebfm_cfgwr_imm_nowt Procedure 15.6.7. ebfm_cfgrd_wait Procedure 15.6.8. ebfm_cfgrd_nowt Procedure 15.6.9. BFM Configuration Procedures 15.6.10. BFM Shared Memory Access Procedures 15.6.11. BFM Log and Message Procedures 15.6.12. Verilog HDL Formatting Functions
15.7.1. Changing Between Serial and PIPE Simulation 15.7.2. Using the PIPE Interface for Gen1 and Gen2 Variants 15.7.3. Viewing the Important PIPE Interface Signals 15.7.4. Disabling the Scrambler for Gen1 and Gen2 Simulations 15.7.5. Disabling 8B/10B Encoding and Decoding for Gen1 and Gen2 Simulations 15.7.6. Changing between the Hard and Soft Reset Controller
8.3. 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.
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/NAK packets
- Data integrity through generation and checking of CRCs for TLPs and DLLPs
- TLP retransmission in case of NAK DLLP reception or replay timeout, using the retry (replay) 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
Figure 65. Data Link Layer
The DLL has the following sub-blocks:
- Data Link Control and Management State Machine—This state machine connects to both the Physical Layer’s LTSSM state machine and the Transaction Layer. It initializes the link and flow control credits and reports status to the Transaction Layer.
- Power Management—This function handles the handshake to enter low power mode. Such a transition is based on register values in the Configuration Space and received Power Management (PM) DLLPs. All of the Arria V Hard IP for PCIe IP core variants do not support low power modes.
- Data Link Layer Packet Generator and Checker—This block is associated with the DLLP’s 16-bit CRC and maintains the integrity of transmitted packets.
- Transaction Layer Packet Generator—This block generates transmit packets, including a sequence number and a 32-bit Link CRC (LCRC). The packets are also sent to the retry buffer for internal storage. In retry mode, the TLP generator receives the packets from the retry buffer and generates the CRC for the transmit packet.
- Retry Buffer—The retry buffer stores TLPs and retransmits all unacknowledged packets in the case of NAK DLLP reception. In case of ACK DLLP reception, the retry buffer discards all acknowledged packets.
- ACK/NAK Packets—The ACK/NAK block handles ACK/NAK DLLPs and generates the sequence number of transmitted packets.
- Transaction Layer Packet Checker—This block checks the integrity of the received TLP and generates a request for transmission of an ACK/NAK DLLP.
- TX Arbitration—This block arbitrates transactions, prioritizing in the following order:
- Initialize FC Data Link Layer packet
- ACK/NAK DLLP (high priority)
- Update FC DLLP (high priority)
- PM DLLP
- Retry buffer TLP
- Update FC DLLP (low priority)
- ACK/NAK FC DLLP (low priority)
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