F-Tile Avalon® Streaming IP for PCI Express* User Guide
ID
683140
Date
10/16/2025
Public
1. Acronyms
2. Introduction
3. IP Architecture and Functional Description
4. Advanced Features
5. Interfaces
6. Parameters
7. Testbench
8. Troubleshooting/Debugging
9. F-Tile Avalon Streaming IP for PCI Express User Guide Archives
10. Revision History for the F-Tile Avalon Streaming IP for PCI Express User Guide
A. Configuration Space Registers
B. Implementation of Address Translation Services (ATS) in Endpoint Mode
C. Packets Forwarded to the User Application in TLP Bypass Mode
D. Root Port Enumeration
E. Bifurcated Endpoint Support for Independent Resets
3.1. Architecture
3.2. Functional Description
3.3. Avalon-ST TX/RX
3.4. Interrupts
3.5. Completion Timeout
3.6. Hot Plug
3.7. Power Management
3.8. Configuration Output Interface (COI)
3.9. Configuration Intercept Interface (EP Only)
3.10. Hard IP Reconfiguration Interface
3.11. PHY Reconfiguration Interface
3.12. Page Request Service (PRS) (EP Only)
5.1. Overview
5.2. Clocks and Resets
5.3. Serial Data Interface
5.4. Avalon-ST Interface
5.5. Interrupt Interface
5.6. Hard IP Status Interface
5.7. Error Interface
5.8. 10-bit Tag Support Interface
5.9. Completion Timeout Interface
5.10. Power Management Interface
5.11. Hot Plug Interface (RP Only)
5.12. Configuration Output Interface
5.13. Configuration Intercept Interface (EP Only)
5.14. Hard IP Reconfiguration Interface
5.15. PHY Reconfiguration Interface
5.16. Page Request Service (PRS) Interface (EP Only)
5.17. FLR Interface Signals
5.18. PTM Interface Signals
5.19. VF Error Flag Interface Signals
5.20. VirtIO PCI Configuration Access Interface Signals
6.2.3.1. Device Capabilities
6.2.3.2. Link Capabilities
6.2.3.3. Legacy Interrupt Pin Register
6.2.3.4. MSI Capabilities
6.2.3.5. MSI-X Capabilities
6.2.3.6. Slot Capabilities
6.2.3.7. Latency Tolerance Reporting (LTR)
6.2.3.8. Process Address Space ID (PASID)
6.2.3.9. Device Serial Number Capability
6.2.3.10. Page Request Service (PRS)
6.2.3.11. Access Control Service (ACS) Capabilities
6.2.3.12. Power Management
6.2.3.13. Vendor Specific Extended Capability (VSEC) Registers
6.2.3.14. Precision Time Measurement (PTM)
6.2.3.15. Address Translation Services (ATS)
6.2.3.16. TLP Processing Hints (TPH)
6.2.3.17. VirtIO Parameters
6.2.3.18. Receiver Detection
7.6.1. ebfm_barwr Procedure
7.6.2. ebfm_barwr_imm Procedure
7.6.3. ebfm_barrd_wait Procedure
7.6.4. ebfm_barrd_nowt Procedure
7.6.5. ebfm_cfgwr_imm_wait Procedure
7.6.6. ebfm_cfgwr_imm_nowt Procedure
7.6.7. ebfm_cfgrd_wait Procedure
7.6.8. ebfm_cfgrd_nowt Procedure
7.6.9. BFM Configuration Procedures
7.6.10. BFM Shared Memory Access Procedures
7.6.11. BFM Log and Message Procedures
7.6.12. Verilog HDL Formatting Functions
3.3.3.1. TX Flow Control
Before a TLP can be transmitted, flow control logic verifies that the link partner's RX port has sufficient buffer space to accept it. The TX Flow Control interface reports the link partner's available RX buffer space to the Application. It reports the space available in units called Flow Control credits for posted, non-posted and completion TLPs (as defined in the RX Flow Control section).
TX credit limit signals are provided in a TDM manner similar to how the RX credit limit signals are provided.
Figure 27. TX Flow Control TDM Reporting of Credit Limits
Figure 28. Buffer Limits Update example
Note: Above is an example showing TX flow control interface is updated when multiple MWr requests are sent. The tx_cdts_limit_o bus value is incremented when a TLP is acknowledged by the receivers and rolls over when reaching 0xFFFF.