For a given configuration, lane decomissioning can be used. The TX SerDes data and stats for decommissioned or unused lanes must be ignored.
For Interlaken configurations whose lanes are covered by FEC, you can decommission lanes in decrements of 2. For configurations without FEC, you can decommission in decrements of 1.
For Interlaken configurations whose lanes are covered by FEC, you can decommission lanes until a minimum of 2 lanes is reached. For configurations without FEC, you can decommission lanes until a minimum of 1 lane is controlled.
Lane decommissioning configuration is through the
c0_ctl_tx_last_lane and c0_ctl_rx_last_lane fields
of CFG_C0_TX_OVERALL_REG and CFG_C0_RX_OVERALL_REG registers.
Refer to the earlier "Summary of Interlaken Configurations" table and
"Configurations Supported by All Speed Grades" table which both contain a "Max # Lanes"
column. For example, if "Max # Lanes" is 12 and FEC is not used on the Interlaken lanes,
then you can set c0_ctl_tx_last_lane /
c0_ctl_rx_last_lane in the range 0 to 11. If "Max # Lanes" is 12
and FEC is actually used on the Interlaken lanes, then only the values 1, 3, 5, 7, 9,
and 11 are legal.