How to change the 1588 PTP reference clock to fpga_ptp_ref_clk in Cyclone V

Hi I am using FAMILY Cyclone V DEVICE 5CSEBA6U23I7 in my design and I an using linuxptp to tune the external PLL, in the first stemp I want to use the fpga_ptp_ref clock from FPGA side,

I tried to use 0xFFD08060 regiater to change the source of the 1588 PTP reference clock to fpga_ptp_ref_clk by writing 0x36 tot he location (default was 0x6) after connecting the 50 MHz clock to hps_0_emac_ptp_ref_clock_clk which is stopping the ToD counter, Is this the right way to change the PTP reference clock? If I change the 0xFFD08060 to 0x6 ToD starts counting with osc1_clk,

what is the right way of changing the 1588 PTP refernce clock?