Visible to Intel only — GUID: biq1702609073340
Ixiasoft
Visible to Intel only — GUID: biq1702609073340
Ixiasoft
6.3.8.1. Application Transmit Flow Control Credit Interface (st_txcrdt)
On the Transmit side, the link partner's receive buffer space information is provided to the application through the Transmit Flow Control Credit Interface for P/F/R-Tiles. Apart from the AXI streaming ready valid handshake, the application logic must check for the availability of credits on the TX flow control credit interface before transmitting the TLP.
Signal Name | Direction | Clock Domain | Description |
---|---|---|---|
ss_app_st_txcrdt_tvalid | Output | axi_st_clk | tvalid indicates that the credit information on tdata is valid. |
ss_app_st_txcrdt_tdata[18:0] | Output | axi_st_clk | Carries the credit limit information and type of credit. [15:0] - Credit Limit Value
[18:16] - Credit Type
|
The figure below shows the credit limit update on the Transmit Flow Control Credit Interface.
In the example below, updated credit limit is output from cycle 9 to cycle 14. When the HOST returns the credit after receiving the packet, the credit limit is incremented by the number of credits returned. At cycle 16, one Posted Header credit is returned. At cycle 19, four Posted Data credits are returned.