Due to a problem in the Clocked Video Input megafunction in the Quartus® II software version 10.1 SP1 and earlier, you may see the following warning when performing static timing analysis in the TimeQuest Timing Analyzer:
Warning: Found combinational loop of 6 nodes
Warning: Node "<user hierarchy>|overflow_nxt~3|combout"
Warning: Node "<user hierarchy>|avalon_st_output.packet_post_swap~0|datab"
Warning: Node "<user hierarchy>|avalon_st_output.packet_post_swap~0|combout"
Warning: Node "<user hierarchy>|overflow_nxt~4|datab"
Warning: Node "<user hierarchy>|overflow_nxt~4|combout"
Warning: Node "<user hierarchy>|overflow_nxt~3|dataa"
This issue may also be flagged as a Critical Design Assistant Warning such as:
Critical Warning: (Critical) Rule A101: Design should not contain combinational loops. Found 1 combinational loop(s) related to this rule.
This problem is scheduled to be resolved in a future release of the Quartus II software.
Although this issue is not expected to cause any functional issues, it is recommended to upgrade to a version of the Quartus II software later than 10.1 SP1 when possible.