The issue with the TLK110 not working in clock out mode with the AM335x is not related to AM335x or the PCB design. CLKOUT on the TLK110 is simply a 50 MHz reference clock that doesn't have any timing relationship to the RMII signals. Therefore, it can not be used as the 50MHz RMII reference clock.
The ICE board has the TLK110 devices connected to the PRU via MII becasue PRU only supports MII.
CPSW in AM335x supports RMII, but with the restrictions discussed in the E2E forum threads you have referenced.
Are you trying to connect the TLK110 to the PRU or CPSW ports in AM335x?
Regards,
Paul
