Achronix Speedster22i Interlaken - Manual (Page 45)

Description of Features
Lane Decommission
The IIPC features two different modes of lane decommissioning:
1. Disabling consecutive lanes, and
2. Disabling a single lane.
Disabling consecutive lanes allows the same instantiation of the IP to be used for multiple
configurations. Disabling a single lane enables lane resiliency where one lane with too many
errors can be disabled in the same physical link. Both modes of decommissioning can be used at
the same time.
There are separate decommissioning controls for the RX and TX paths to allow system designers
to optimize performance by creating asymmetric links. The operation is similar for both RX and
TX paths and is described below.
Disabling Consecutive Lanes
Consecutive Transmit Lanes
Disabling consecutive transmit lanes is achieved by simply setting the ctl_tx_last_lane parameter
to the number of the last active SerDes lane. For example, for an 8 serial lane Interlaken link,
ctl_tx_last_lane would normally be set to a value of 7 since the lanes are numbered 0 to 7. If only 4
lanes are required, ctl_tx_last_lane should be assigned a value of 3. This causes the corresponding
path to only use lanes 0 to 3.
The minimum value for the last lane is dependent on the internal configuration of the core.
The value of ctl_tx_last_lane must only be changed when the TX path is held in reset.
Consecutive Receive Lanes
Disabling consecutive receive lanes is identical to disabling consecutive transmit lanes except the
ctl_rx_last_lane parameter is used instead.
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