owr_dl: Verification Plan¶

1. Overview¶

The Data Link layer is verified together with the Encoding layer at the line: port A against the Data-Strobe far-end model, which sends any character sequence (also sequences a correct port never sends) and logs every character of port A, and port A against a second port B for traffic. Tests observe the ports, the status outputs and the line only.

2. Test configuration¶

Testbench	Harness	DUT and environment
`owr_dl_tb`	`owr_dl_th`, `owr_dl_tb_port`	Ports A and B (each `owr_enc` + `owr_dl`, FIFOs of 64), LinkClk 100 MHz, UserClk 83.3 MHz, far-end model at 10 Mb/s on the line of A (`LinkMode` = '0') or B (`LinkMode` = '1'), `Cut` freezes both directions, AXI4-Stream VVCs on the N-Char ports (TLAST = marker beat), counters of the status events

Simulator: GHDL. The run divider of the ports is 1 (100 Mb/s) unless stated.

3. Test cases¶

Test ID	Description	Requirements
`test_lsm_startup` (TC-DL-01)	ErrorReset 5.82 to 7.22 us and ErrorWait 11.64 to 14.33 us after reset; Started on LinkStart and its timeout without far end; with Nulls: only Nulls in Started, Connecting, seven FCTs, no N-Char, Run on one FCT; credits 8 and 56	DL-LS-01 to DL-LS-07, DL-FC-01, DL-FC-03, DL-FC-04, DL-IF-03, DL-IF-04, DL-IF-05, DL-IF-06, DL-TX-01, DL-TX-02
`test_lsm_autostart` (TC-DL-02)	AutoStart waits in Ready without a Null, starts on gotNull	DL-LS-04, DL-IF-05
`test_lsm_disabled` (TC-DL-03)	LinkDisabled keeps ErrorReset with the receiver disabled; LinkDisabled in Connecting, Run (with recovery and cause), ErrorWait, Ready and Started	DL-LS-01 to DL-LS-07, DL-RC-01
`test_lsm_timeouts` (TC-DL-04)	Started and Connecting time out after 11.64 to 14.33 us	DL-LS-05, DL-LS-06
`test_lsm_errors` (TC-DL-05)	FCT, N-Char and broadcast code received in ErrorWait and Ready; parity error, ESC error and disconnect in Ready; N-Char, broadcast code (not stored, not passed) and disconnect in Connecting; parity error, ESC error and disconnect in Run with recovery and cause	DL-LS-01, DL-LS-03, DL-LS-04, DL-LS-06, DL-LS-07, DL-RX-01, DL-RC-01
`test_port_reset` (TC-DL-06)	Port reset in Run clears both FIFOs, credits and the state; the link restarts; port reset during a recovery that waits for the end of a packet returns to Normal and stops the discard	DL-LS-08, DL-FI-01, DL-FI-02, DL-RC-02
`test_fc_rx_credit` (TC-DL-10)	Seven FCTs for a FIFO of 64; no FCT while the FIFO has no room for 8 more; one FCT after reading 8 N-Chars; the full credit of 56 received without reading; seven FCTs after reading	DL-FC-03, DL-FC-04
`test_fc_tx_credit` (TC-DL-11)	Exactly 8 N-Chars per FCT received; transmit credit counter	DL-FC-01, DL-FC-02, DL-TX-01
`test_fc_credit_errors` (TC-DL-12)	FCT raising the transmit credit above 56; N-Char with a receive credit of zero: credit error, ErrorReset, cause, the N-Char not stored, EEP after the data	DL-FC-05, DL-RC-01, DL-RX-02
`test_tx_priority` (TC-DL-20)	Broadcast code, FCT request and N-Chars pending at one character boundary: sent in the order broadcast code, FCT, N-Chars	DL-TX-01, DL-TX-03
`test_bc_service` (TC-DL-21)	Broadcast code outside Run discarded and reported; four codes in Run sent; received time-code and interrupt code passed in Run; a code waiting in the slot is discarded in ErrorReset	DL-TX-03, DL-RX-01, DL-IF-02
`test_rec_tx_discard` (TC-DL-30)	Disconnect after 8 of 100 data characters: the rest of the packet is discarded from the transmit FIFO, the next packet is sent complete after the restart; cause disconnect	DL-TX-04, DL-RC-01
`test_rec_rx_eep` (TC-DL-31)	Parity error after data characters: the data confirmed by a parity check followed by an EEP; ESC error after a complete packet: no EEP; causes	DL-RX-02, DL-RC-01
`test_rec_restart` (TC-DL-32)	Disconnect in the middle of a packet whose source pauses; the link returns to Run while the remainder is discarded; a parity error in Run restarts the recovery with the new cause; the recovery ends when the remainder up to the EOP is discarded, nothing of it is sent, the next packet is sent complete	DL-RC-01, DL-TX-04
`test_link_traffic` (TC-DL-40)	Ports A and B: 60 packets of 0 to 300 bytes in each direction with EOP and EEP; 20 packets of 1000 bytes at 100 Mb/s at 95 % or more of 8 Mb/s user data per 10 Mb/s	DL-IF-01, DL-FI-01, DL-TX-01, DL-RX-01
`test_link_backpressure` (TC-DL-41)	Random gaps on the transmit side and random back-pressure on the receive side, 50 packets	DL-IF-01, DL-FC-04
`test_link_restart` (TC-DL-42)	Line cut for 3 us in the middle of a packet: both ports restart, the packet arrives as a prefix with EEP, the following packets are complete	DL-TX-04, DL-RX-02, DL-RC-01
`test_ecc_tx` (TC-DL-50)	Single error injected into the transmit FIFO corrected and counted; double error: EEP sent, rest of the packet discarded, next packet complete	DL-TX-05
`test_ecc_rx` (TC-DL-51)	Single error injected into the receive FIFO corrected and counted; double error: EEP passed, rest of the packet discarded, next packet complete	DL-FI-03

4. Requirement coverage¶

Requirement	Test cases
DL-IF-01	TC-DL-40, TC-DL-41
DL-IF-02	TC-DL-21
DL-IF-03, DL-IF-04, DL-IF-06	TC-DL-01
DL-IF-05	TC-DL-01, TC-DL-02
DL-FI-01	TC-DL-06, TC-DL-40
DL-FI-02	TC-DL-06
DL-FI-03	TC-DL-51
DL-LS-01 to DL-LS-07	TC-DL-01, TC-DL-03, TC-DL-04, TC-DL-05
DL-LS-08	TC-DL-06
DL-FC-01	TC-DL-01, TC-DL-11
DL-FC-02	TC-DL-11
DL-FC-03, DL-FC-04	TC-DL-01, TC-DL-10
DL-FC-05	TC-DL-12
DL-TX-01	TC-DL-01, TC-DL-11, TC-DL-20
DL-TX-02	TC-DL-01
DL-TX-03	TC-DL-20, TC-DL-21
DL-TX-04	TC-DL-30, TC-DL-32, TC-DL-42
DL-TX-05	TC-DL-50
DL-RX-01	TC-DL-05, TC-DL-21, TC-DL-40
DL-RX-02	TC-DL-12, TC-DL-31, TC-DL-42
DL-RC-01	TC-DL-03, TC-DL-05, TC-DL-12, TC-DL-30, TC-DL-31, TC-DL-32
DL-RC-02	TC-DL-06

5. Negative tests¶

Checker	Test
Received character outside Run	TC-DL-05
Started and Connecting timeouts	TC-DL-04
Transmit credit overflow, N-Char without credit	TC-DL-12
Broadcast code outside Run	TC-DL-21
Double error in the transmit and receive FIFO	TC-DL-50, TC-DL-51