Ethernet Interface to Micrel KSZ9021 PHY.

Added by Raja Vankam over 9 years ago


We are using MityARM SOM and MICREL KSZ9021RNI gigabit as PHY on it for Ethernet Interface.
We have configured ETH_RXD0, ETH_RXD1, ETH_RXD2, ETH_RXD3, ETH_RXCTL as pullup high on PHY reset to get mode[3 -0] to 0xF (RGMII Mode – advertise all capabilities (10/100/1000 speed half/full duplex).) and enable clock 125.
However we are not getting link up also we are not getting 125MHZ clk on CLK125_NDO Pin on the PHY.
The TX_CLK from controller to PHY is 2.5MHZ and RX_CLK is always low, not sure if this is reason why 125MHZ clock output not getting generated.

Let me know if I have missed anything in configuring PHY.

Appreciate your response.


Replies (1)

RE: Ethernet Interface to Micrel KSZ9021 PHY. - Added by Michael Williamson over 9 years ago

Hi Raja,

I don't think we've used this PHY with the MityARM-3359 here, but we have had problems strapping this device on other designs. The AM3359 has several pins pulled down (or up) after a power on reset. You should check Table 2-7 of the AM3359 specification to see what states the AM3359 pins come up in after a reset.

In the past, we have had to (using u-Boot or other software) either ensure that the pull-ups are disabled and then toggle a reset to the PHY after power up or use the SPI interface and re-write the configuration in order to ensure proper operation.

I suspect this may be your issue.


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