Why does the Video Frame Write sometimes issue a write request to the AXI-MM interface even when there is no data to write?
This is a known issue that applies to the Video Frame Buffer Write v2.0 (Rev. 1) and earlier in Vivado 2017.4 and earlier.
This has been resolved in the Video Frame Buffer Write v2.0 (Rev. 2) and later in Vivado 2018.1 and later.
To work around this issue, you can put an AXI Data FIFO on the output of the Frame Buffer Write AXI MM Interface and set WRITE FIFO DEPTH to 512 and WRITE FIFO DELAY to ON.
It is also recommended to configure the AXI Interconnect to Maximize Performance.
An example of this work-around can be seen in the example design which is packaged with the IP.
Information on how to generate the example design can be found in the Video Frame Buffer Product Guide (PG278) with the Video Frame Buffer v2.0 (Rev. 1) and earlier in Vivado 2017.4 and earlier.