Linux/AM3352: About Ethernet Loopback Test Issue

yimin bai34

Genius 4755 points

Part Number: AM3352

Tool/software: Linux

Hi Sir

We used Linux SDK with AM3352 to do development and did loopback test function.in u-boot.

We found AM3352 cannot receive tx packet during loopback test and doubted CPU ignored the packets it sent.

BTW, we found below API in net/eth-uclass.c file which would return "-16" .

ret = eth_get_ops(current)->recv(current, flags, &packet);

please advise how to let AM3352 not to ignore/remove loopback packet while receiving packet from itself.

Yimin

over 6 years ago

0 Biser Gatchev-XID over 6 years ago

TI__Guru**** 393215 points

Please post what Linux version you use.

0 yimin bai34 over 6 years ago in reply to Biser Gatchev-XID

Genius 4755 points

Hi Sir

We used ti-processor-sdk-linux-am335x-evm-04.02.00.09

BR
Yimin

0 yimin bai34 over 6 years ago in reply to Biser Gatchev-XID

Genius 4755 points

Hi Sir
Do you have any update

BR
Yimin

0 Schuyler Patton over 6 years ago in reply to yimin bai34

TI__Mastermind 38770 points

Hi,

Assuming that you are using the CPSW interface based on the part number. Could you please though confirm which Ethernet interface are you using? To my knowledge we do not support loopback features of the part in either u-boot or Linux and therefore for this may not work for your needs.

What type of loopback are you trying to do? The part supports in internal loopback which looks like never leaves the port. Or is there a board issue that you are trying to isolate?

Best Regards,
Schuyler

0 yimin bai34 over 6 years ago in reply to Schuyler Patton

Genius 4755 points

Hi Sir

1. We used EMAC0 of AM3352 to connect QCA8337 PHY and wanted to do external loopback test as below

2. We used non-TI CPU and can do above loopback test without issue.

3. Can AM3352 do external loopback test as above photo described. if not, how to do CPU internal loopback test ?

please advise

BR
Yimin

0 yimin bai34 over 6 years ago in reply to Schuyler Patton

Genius 4755 points

Hi Sir

Do you have any update

Yimin

0 Schuyler Patton over 6 years ago in reply to yimin bai34

TI__Mastermind 38770 points

Hi,

Thank you for the diagram. Based on the diagram it looks to me like you want FIFO Loopback described in this section of the TRM.

This section describes the FIFO loopback which loops back RX to the TX

14.3.2.19 FIFO Loopback

This is the register that sets it :

14.5.7.2 MACCONTROL Register (offset = 4h) [reset = 0h]

Bit 1:

Loop Back Mode - Loopback mode forces internal fullduplex mode regardless of whether the fullduplex bit is set or not. The loopback bit should be changed only when GMII_en is deasserted. 0 - Not looped back 1 - Loop Back Mode enabled

Best Regards,

Schuyler

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Linux/AM3352: About Ethernet Loopback Test Issue