A. RGMII[x]_RCLK must be externally delayed relative to the RGMII[x]_RD[3:0] and RGMII[x]_RCTL signals to meet the respective timing requirements.
B. Data and control information is received using both edges of the clocks. RGMII[x]_RD[3:0] carries data bits 3-0 on the rising edge of RGMII[x]_RCLK and data bits 7-4 on the falling edge of RGMII[x]_RCLK. Similarly, RGMII[x]_RCTL carries RXDV on rising edge of RGMII[x]_RCLK and RXERR on falling edge of RGMII[x]_RCLK.
Figure 7-14 RGMII[x]_RD[3:0], RGMII[x]_RCTL Timing - RGMII Mode