SPRUIU1C July 2020 – February 2024 DRA821U , DRA821U-Q1
Ethernet ports transmit each egress packet with the CRC selected by the CRC_TYPE bit in the CPSW_PN_MAC_CONTROL_REG_k register, regardless of the type of CRC that the packet had on ingress to the switch. At the egress port after passing through the switch, the packet CRC is checked for correctness and if the CRC is correct then the packet is output with the generated selected output CRC. If the packet CRC is incorrect, due either to a bit flip in a memory or an error CRC passed in on host ingress, then the generated egress CRC type is used with at least a single byte of the CRC inverted to indicate the error. If the packet length including CRC is divisible by 4 then all 4 CRC bytes will be inverted on error. If there are three bytes remainder after dividing the packet length by 4 then three bytes will be inverted (and so on down to one byte remainder).