We've been having problems with Ethernet comms on our custom board……
The root of the problem is the need for a pull down on the TCK pin, as per TI Advisory note 1.1.4. I added this and the port started to behave itself instantly.
Figure Workaround Example
Revision(s) Affected Details
3-Port Ethernet Switch Subsystem (3PSW) clocking problem normal functional operation earlier (JTAG controller clock) internally shared 3-Port Ethernet Switch Subsystem's (3PSW) STCICLK test debug mode. order 3-Port Ethernet Switch Subsystem (3PSW) proper clocking normal functional operation, STCICLK needs held low. since there internal pullup TCK, keeps 3-Port Ethernet Switch Subsystem from locking external REFCLKP/N proper operation. should externally pulled down with resistor.