It is observed in a very rare failing case where the PCAP DMA hangs or the system goes to an unknown state when FSBL is attempting to load the corrupted PS/application encrypted partition image.
The PCAP DMA is able to do another transfer only after asserting system reset (SLCR PS reset).
Please visit the Zynq-7000 SoC Solution Center (Xilinx Answer 52512) to address all questions related to the Zynq-7000 SoC.
It is known that one of the following situations will cause the PCAP DMA to hang:
This is somewhat documented in the TRM and the only way to un-hang the PCAP DMA is to POR/SRST the device.