[Etherlab-users] EoE in userspace - Other mailbox response

[Bernhard Vorhofer]

Dear all,

we're currently investigating some issues with a particular slave (BBH
SCU-2-EC FSoE Master). There are multiple issues (sometimes the slave
refuses state change to OP, for example), but something that piqued our
interest be seen in the following log excerpt:

kernel: EtherCAT DEBUG 0: ecrt_master_sdo_upload(master =
0x00000000d53d8735, slave_position = 0, index = 0x4002, subindex =
0x00, target = 0x00000000f9b1cb01, target_size = 40, result_size =
0x000000007e76960b, abort_code = 0x000000002d1055bf)
kernel: EtherCAT DEBUG 0-0: Scheduling SDO upload request.
kernel: EtherCAT DEBUG 0-0: Processing SDO request...
kernel: EtherCAT DEBUG 0-0: Uploading SDO 0x4002:00.
kernel: EtherCAT DEBUG 0-0: Upload request:
kernel: EtherCAT DEBUG: 00 20 40 02 40 00 00 00 00 00
kernel: EtherCAT DEBUG 0-0: Upload response:
kernel: EtherCAT DEBUG: 00 30 41 02 40 00 28 00 00 00 00 74 0B 00 DF 8C
kernel: EtherCAT DEBUG: CC 04 00 00 00 00 00 00 80 3F 00 00 00 00 00 00
kernel: EtherCAT DEBUG: 00 00 00 00 00 00 00 00 00 00 00 00 80 3F 00 00
kernel: EtherCAT DEBUG: 00 00
kernel: EtherCAT DEBUG 0-0: Uploaded data:
kernel: EtherCAT DEBUG: 00 74 0B 00 DF 8C CC 04 00 00 00 00 00 00 80 3F
kernel: EtherCAT DEBUG: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
kernel: EtherCAT DEBUG: 00 00 80 3F 00 00 00 00
kernel: EtherCAT DEBUG 0-0: Finished SDO request.
kernel: EtherCAT DEBUG 0: ecrt_master_sdo_upload(master =
0x00000000d53d8735, slave_position = 0, index = 0x4002, subindex =
0x00, target = 0x00000000f9b1cb01, target_size = 40, result_size =
0x000000004af47ed5, abort_code = 0x00000000d0acc148)
kernel: EtherCAT DEBUG 0-0: Scheduling SDO upload request.
kernel: EtherCAT DEBUG 0-0: Processing SDO request...
kernel: EtherCAT DEBUG 0-0: Uploading SDO 0x4002:00.
kernel: EtherCAT DEBUG 0-0: Upload request:
kernel: EtherCAT DEBUG: 00 20 40 02 40 00 00 00 00 00
kernel: EtherCAT WARNING 0-0: Other mailbox protocol response for eoe0s0.
kernel: EtherCAT ERROR 0-0: Timeout after 1000 ms while waiting for
SDO 0x4002:0 upload response.
kernel: EtherCAT ERROR 0-0: Failed to process SDO request.

The first SDO request is successful, the second one times out. Right before
the timeout, the message "Other mailbox protocol response for eoe0s0"
appears. It seems that the SDO response somehow ends up in the EoE thread,
is dropped there and thus lost.

Are we interpreting this behavior correctly? Is there anything that can be
done to prevent this from happening, and could this cause some other issues
we're seeing (slave refusing to go to OP due to "Invalid input
configuration")?

We've seen the function `ecrt_master_callbacks`, but it seems that it's
only relevant in case the application is run in a kernel module. Our
application runs in a userspace process.

Thank you very much and best regards,
Bernhard Vorhofer
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