Some FMC boards do utilize more than one transceiver quad but do not
necessarily use all transceivers in a quad. On such board is the
AD9694-500EBZ. Which uses two transceivers each in two adjacent quads.
This board can not be supported by instantiating a util_adxcvr with only 4
lanes. Since those 4 lanes would be packed into the same quad. Instead it
it is necessary to instantiate a util_adxcvr with 6 lanes. 4 lanes for the
first quad and 2 for the second.
To still to be able to connect such a util_adxcvr to a link layer with only
4 lanes allow to specify sparse lane mappings. A sparse mapping can have
less lanes than the util_adxcvr and some lanes will be left unconnected.
For example for the AD9694-500EBZ the lane mapping looks like the following:
ad_xcvrcon util_ad9694_xcvr axi_ad9694_xcvr ad9694_jesd {0 1 4 5} rx_device_clk
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
9b01b9f37c