DP83TC812S-Q1: DP83TC812SRHARQ1: how to set the RX_CLK output automatically and continuously,in RGMII mode

Part Number: DP83TC812S-Q1


when DP83TC812 works on RGMII mode,how to set  RX_CLK(pin27) output 25MHZ clk automatically and continuously,after POR finished.

SOC need to detect  RX_CLK,if there is no output singal,SOC will report 'DMA engine initialization failed'error.