At power-up, I need to run the Virtex GTP at 400Mbps and then after the initialization, I need to run the V5 GTP at 3.2 Gbps.
In order to keep it simple, I am thinking about running the V5 GTP at 3.2 Gbps all the time - even at power-up.
Thus to achieve the lower data rate of 400Mbps, I plan to write the same data 8 times (3200Mbps/400Mbps). The FPGA fabric state machine will write the data to be sent to the GTP into a deep dual port fifo. The logic on the GTP side will retrieve the data from the fifo and write to the GTP parallel data input 8 times.
Please let me know if there is a better way to do this then this.