SPRUIV7B May 2022 – September 2023 AM620-Q1 , AM623 , AM625 , AM625-Q1 , AM625SIP
Each of the two CPSW_2G ports has an identical associated FIFO. Each FIFO contains a single logical receive queue and eight logical transmit queues (priority 0 through 7 with 7 the highest priority). Each FIFO memory contains 20,480 bytes (20k) total organized as 2560 by 64-bit words contained in a single memory instance. The FIFO memory is used for the associated port transmit and receive queues. The TX_MAX_BLKS field in the FIFOs associated CPSW_PN_MAX_BLKS_REG register determines the maximum number of 1k FIFO memory blocks to be allocated to the eight logical transmit queues (transmit total). The RX_MAX_BLKS field in the FIFO's associated CPSW_PN_MAX_BLKS_REG register determines the maximum number of 1k memory blocks to be allocated to the logical receive queue. The TX_MAX_BLKS value plus the RX_MAX_BLKS value must sum to 20 (the total number of blocks in the FIFO). If the sum were less than 20, then some memory blocks would be unused. The default is 17 (decimal) transmit blocks and three receive blocks. The FIFOs follow the naming convention of the Ethernet ports. Host Port is Port0 and External Ports is Port1.
Each transmit FIFO contains a configurable number of blocks (20 max) that are either 1k or 4k byte blocks that can be allocated to any priority.