Hello Mr. Oliver Hartkopp, I would like to notify you that the case described as the issue is caused by non-standard use of the device and protocol. Firstly, the model situation with only a single device on the CAN bus is invalid and very rarely occurs in real life due to the purpose and underlying principles of the CAN2.0 protocol. Every CAN message sent to the bus should be acknowledged by other bus node(s) or it will increment the error counter and will be retransmitted. The proper usage of a single device (e. g. for testing or self-diagnostic purposes) would be to enable loopback mode on when initialising the device in question, as that will ensure that the device acknowledges the messages it sends to the bus. Secondly, usage of termination resistors is a must on a CAN bus, and according to ISO 11898-2 (CAN High Speed) standard the bus is a linear bus that must be terminated at each end with 120 Ohm resistors. The termination resistors are needed to suppress reflections as well as return the bus to its recessive or idle state. Moreover, the kernel warnings appear to be caused by the socketCAN layer using netif_rx() function inside an interrupt, they can be easily recreated using the obsoleted first generation USB2CAN device and most likely any other device using socketCAN. Finally, TX URB aborted(-2) errors are expected in the described scenario as error code -2 (-ENODEV) simply notifies that the specified device for the URB to be submitted no longer exists (as is expected when device is brought down). Taking into account the findings above we will close this ticket as the issue was caused by non-standard usage of the device. Best regards, Andrejus F.
