Maximum supported LP Clock in SDR mode is 125 MHz.
Maximum supported LP clock in DDR mode is 250 MHZ.
Sources of CDU CLKO9 is OCLK_0, DCLK_0 and SYSCLK_1. If you want to configure LP_DDR clock more than 125 MHZ, then you should use DCLK_0 or SYSCLK_1 as input clock source for CDU CLKO9 as OCLK_0 maximum supported frequency is 125 MHZ.