Enable_unused_rx_clock_workaround

Can someone please tell me what this constraint does and when it is needed? Searching on the Altera site only pulls up this:

https://www.altera.com/support/support-resources/knowledge-base/solutions/fb325122.html

Not a lot of information there. We're developing on the Arria 10 SoC dev kit and so far the .qsf files for all of the reference designs we have downloaded include some variation of the following:

set_instance_assignment -name ENABLE_UNUSED_RX_CLOCK_WORKAROUND ON -to AE33

set_instance_assignment -name ENABLE_UNUSED_RX_CLOCK_WORKAROUND ON -to AD31

set_instance_assignment -name ENABLE_UNUSED_RX_CLOCK_WORKAROUND ON -to AD35

set_instance_assignment -name ENABLE_UNUSED_RX_CLOCK_WORKAROUND ON -to AC33

set_instance_assignment -name ENABLE_UNUSED_RX_CLOCK_WORKAROUND ON -to AB31

set_instance_assignment -name ENABLE_UNUSED_RX_CLOCK_WORKAROUND ON -to AB35

set_instance_assignment -name ENABLE_UNUSED_RX_CLOCK_WORKAROUND ON -to AA33

set_instance_assignment -name ENABLE_UNUSED_RX_CLOCK_WORKAROUND ON -to Y35

set_instance_assignment -name ENABLE_UNUSED_RX_CLOCK_WORKAROUND ON -to AG33

set_instance_assignment -name ENABLE_UNUSED_RX_CLOCK_WORKAROUND ON -to AH35

None of the reference designs includes the JESD204B core. The number of pins constrained seems to vary depending on how many transceivers are used in the reference design.

Why is this constraint not documented anywhere, at least not that I can find?

Thanks,

Bob