In the example in This Figure, the driver in the host is considered to be the master. It can enable/disable/reset a DMA channel. Hence, a handshake is required between the host software and AXI-CPU software to indicate DMA reset/channel enable/disable events. The scratch pad registers available per DMA channel can be used for communication of a handshake event with signature values written to convey the meaning. This is typically based on a predefined messaging protocol between the two software drivers.