MPC8548 eTSEC truncated Tx frame exceeds MAXFRM

[robertbracero]

During MPC8548 Ethernet testing, we have observed that when a Tx frame is truncated, the eTSEC always sends exactly (MAXFRM + 5) bytes. It doesn’t matter how many bytes over MAXFRM you were trying to send (1, 1000, etc…). Looking at the extra 5 bytes, the first one is an extra valid data byte from the transmit buffer (i.e. txbuf[MAXFRM]). The last 4 look random. They are not data and they are not a valid CRC. Is this the expected MPC8548 eTSEC behavior?

[bpe]

Can you please provide the following information:

1. Your  MPC8548 silicon revision.

2. NXP SDK/BSP version you are working with, if at all

3. Is this a custom board or CDS? If custom, please specify the
   model of the PHY  

4. Do all eTSECs exhibit this behaviour or only one?

5. Please share a register dump of the problematic eTSEC,
   taken after the problem manifests itself. Please include the
   following areas: eTSEC general config registers(0x2_4000 to 0FF),
   MAC registers (offset 0x2_4500 to 5BF)

[robertbracero]

We have tested this on the CDS8548 board as well and confirmed that 5 extra bytes always get sent when Tx truncation occurs. The pvr is 0x80210020, and in this case all 5 bytes are always 0x0e.

[robertbracero]

1. pvr=0x80210022

2. Green Hills Software INTEGRITY BSP

3. This is a custom board with a TLK100 PHY

4. Only one eTSEC is brought out on this board (eTSEC3)

5. Attached is the raw memory dump of the eTSEC register block (0x2_6000 – 0x2_6FFF) immediately after sending a truncated Tx frame.