Visible to Intel only — GUID: coa1613084482044
Ixiasoft
Visible to Intel only — GUID: coa1613084482044
Ixiasoft
4.4.1.2.5. TX Flow Control Interface
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 Interface section).
For more information on how credit control in general is implemented in this IP, refer to Credit Control.
Signal Name | Direction | Description | EP/RP/BP | Clock Domain |
---|---|---|---|---|
pX_tx_st_hcrdt_update_o[2:0] where X = 0, 1, 2, 3 (IP core number) |
Output | Indicates credit is made available for the different types of Header. Each Header (including the TLP Prefix, if any) consumes one credit. [0] : Posted Header (PH) [1] : Non-Posted Header (NPH) [2] : Completion Header (CPLH) When the link partner advertises infinite credits, this signal will get asserted for one clock cycle, with a value of 0 on pX_tx_st_hcrdt_update_cnt_o during the credit initialization phase. |
EP/RP/BP | coreclkout_hip |
pX_tx_st_hcrdt_update_cnt_o[5:0] where X = 0, 1, 2, 3 (IP core number) |
Output | Indicates number of credits released. [1:0] : number of PH credits released [3:2] : number of NPH credits released [5:4] : number of CPLH credits released Valid when the corresponding pX_tx_st_hcrdt_update_o bit = 1. The maximum number of credits released is three. When the link partner advertises infinite credits, this signal will reflect a 0 during the credit initialization phase (when pX_tx_st_hcrdt_update_o is asserted for one clock cycle). |
EP/RP/BP | coreclkout_hip |
pX_tx_st_hcrdt_init_o[2:0] where X = 0, 1, 2, 3 (IP core number) |
Output | Credit Initialization indicator. These signals remain high for entire initialization phase. A High to Low transition indicates the completion of the credit initialization phase. [0] : PH [1] : NPH [2] : CPLH |
EP/RP/BP | coreclkout_hip |
pX_tx_st_hcrdt_init_ack_i[2:0] where X = 0, 1, 2, 3 (IP core number) |
Input | Indicates the Application logic is ready for the credit initialization phase [0] : PH [1] : NPH [2] : CPLH |
EP/RP/BP | coreclkout_hip |
pX_tx_st_dcrdt_update_o[2:0] where X = 0, 1, 2, 3 (IP core number) |
Output | Indicates credit is made available for the different types of Data. [0] : Posted Data (PD) [1] : Non-Posted Data (NPD) [2] : Completion Data (CPLD) When the link partner advertises infinite credits, this signal will get asserted for one clock cycle, with a value of 0 on pX_tx_st_dcrdt_update_cnt_o during the credit initialization phase. |
EP/RP/BP | coreclkout_hip |
pX_tx_st_dcrdt_update_cnt_o[11:0] where X = 0, 1, 2, 3 (IP core number) |
Output | Indicates number of credits released. [3:0] : number of PD credits released [7:4] : number of NPD credits released [11:8] : number of CPLD credits released Valid when the corresponding pX_tx_st_dcrdt_update_o bit = 1. The maximum number of credits released is 15. When the link partner advertises infinite credits, this signal will reflect a 0 during the credit initialization phase (when pX_tx_st_dcrdt_update_o is asserted for one clock cycle. |
EP/RP/BP | coreclkout_hip |
pX_tx_st_dcrdt_init_o[2:0] where X = 0, 1, 2, 3 (IP core number) |
Output | Credit Initialization indicator. These signals remain high for entire initialization phase. A High to Low transition indicates the completion of the credit initialization phase. [0] : PD [1] : NPD [2] : CPLD |
EP/RP/BP | coreclkout_hip |
pX_tx_st_dcrdt_init_ack_i[2:0] where X = 0, 1, 2, 3 (IP core number) |
Input | Indicates the Application logic is ready for the credit initialization phase [0] : PD [1] : NPD [2] : CPLD |
EP/RP/BP | coreclkout_hip |