In (PG231) v2.1 published on May 22, 2019 (and earlier versions), it is stated that the Video Processing Subsystem (VPSS) IP expects the tuser (SOF) to be asserted every field on the input side:
"The Start-Of-Frame (SOF) signal, physically transmitted over the AXI4-Stream TUSER signal, marks the first pixel of first incoming video field at slave/input side and first pixel of every outgoing video frame at the master/output side."
However, in the corresponding figure, figure 3-1, the input (or slave) SOF is asserted only every frame (i.e. every 2 fields).
This diagram is incorrect, please see the updated Product Guide dated December 17, 2019 and later.
Figure 3-1 is incorrect. The VPSS expects the SOF signals on its inputs to be asserted every field for interlaced content.