SPRUIU1C July 2020 – February 2024 DRA821U , DRA821U-Q1
The PCIe Subsystem allows mapping of PCIe addresses to/from the internal bus addresses of the device. This is accomplished by using internal address translation unit (iATU) in the PCIe core. For each outbound read/write request, the address translation module within PCIe subsystem can convert a VBUSM address to a PCIe address of memory Read/Write type.
If a transaction is large enough that it goes past the address translation region, unspecified behavior may occur. The address translation only works at the time a command is issued. So, a memory write, for example, will not automatically go to next translation region, if it starts in the previous one and is bigger than the remaining size in the starting translation region.
The “Dynamic Method: Sideband Descriptor Based” outbound address translation mechanism is used to bypass the outbound address translation unit under certain conditions. For more details on the bypass operation, see Section 12.2.3.4.7.2.1, PCIe Outbound Address Translation Bypass.