AM3358: AM3358 + AR8031 ping time out problem

Part Number:AM3358

Hello，TI

I have three AM335x developed board,(AM335x Starter Kit/MYIR AM3358-J/Self-developed AM3358 board)，there are some problems when I use network port:

• AM335x Starter Kit(TMDSSK3358) have two AR8031 PHY IC, and I use the default android system and connect the port directly to PC  to test dual 1000M network.
  • both eth0 and eth1 can run at 1000M mode, and both eth ping with 65000 byte data length(pattern 0X00) is OK
  • when I use “ping ip -p 0xf0 -s 65000” to test eth1, the probability of time out is about(1~5%) , but eth0 is alway function good.

• Then I run MYIR AM3358-J board(http://www.myir-tech.com/product/myd-am335x-j.htm)  under the same test conditions,  MYIR AM3358-J adopt stwo AR8035 solution and there is no time out in both eths when ”ping ip -p 0xf0 -s 65000“

finally we designed a AM3358 board with a AR8031 and a AR8035(AR8031 run in 1000M mode/AR8035 run in 100M mode) with own software, the shematic of AR8031 and the RGMII interfaces pinmux is exactly the same to TMDSSK3358

• the both eth1(AR8031/1000M) and eth0(AR8035/100M) of self-dev AM3358 board can be link up/down normally
• when I set eth1 at 1000M mode, ping with 65000 byte data length(pattern 0X00) is OK
• when I set eth1 at 1000M mode, ping with 65000 byte data length(pattern 0XF0)  the probability of time out is about(95%), then I find that when I ping with patern 0XF0 and the data length is >700 bytes, the ping test is most likely  failed
• when I set eth1 at 100M mode, it works good at any ping test conditions

• when I capture the TX_EN signal with oscilloscope, I find that both TMDSSK3358 and self-dev board have a 250MHz signal in TX_EN line, fig1 shows TX_EN in self-dev board; fig2 shows TX_EN in TMDSSK3358  board (under ping ip -p 0xf0 -s 65000 condition)

fig 1

fig 2

• I'm curious why self-dev board ping with pattern 0XF0 data length>700 is alway failed and why there exists a 250MHz signal? Could you give me some advise?