ID:12505 LVDS RX channel in DPA mode is only supported with rx_dpll_hold for data rate range from 0.841 Gbps to 1.219 Gbps. For more details, refer to the <family> errata sheet

CAUSE: The rx_dpll_hold port is disabled for an LVDS RX channel in DPA mode with data rate range from 0.841 Gbps to 1.219 Gbps.

ACTION: Enable the rx_dpll_hold port in the ALTLVDS megafunction and assert this port after the initial DPA lock in your design. For more details, refer to the device family errata sheet, or contact Intel for support.