20b/40b and 32b/64b PHY Usage

You use 20b/40b PHY data transfer for 8b/10b encoding/decoding protocols, and 32b/64b PHY data transfer for scrambled data patterns requiring a polynomial order of 23 and above. This limitation is due to the additional PMA RX CTLE adaptation level required in 32b/64b PHY, which needs a frequency-rich data pattern to lock to the correct boundary. Using 32b/64b PHY to transfer 8b/10b encoding data patterns can result in the RX forming an unstable lock to the wrong data boundary upon power up/reset.