SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
A memory management unit (MMU) is a hardware component responsible for handling accesses to memory requested by a processing unit, DMA controller, or other bus requestor. MMU functions include:
This device includes the following MMUs:
There is a Physical Address Translator (PAT) module in the Dynamic Memory Manager (DMM), which has similar to the MMU functionality. For more information about this module, see Section 15.2, Dynamic Memory Manager.
This chapter provides a detailed description of the following MMUs:
System MMUs, DSP MMUs and EVE MMUs are fully identical from functional perspective. IPU L2 MMU is different in that it does not support “bypass” functionality.
For more information about:
Figure 20-1 and Figure 20-2 show an overview of system MMU1 and MMU2, respectively. In summary, requests initiated by a given requestor (EDMA TC0 and TC1 [both read and write ports] for system MMU1; PCIe_SS1 and PCIe_SS2 for system MMU2) can optionally be routed through the corresponding system MMU. Each requestor’s use (or not) of the MMU is independently controllable via the Control Module CTRL_CORE_SMA_SW_7 register bitfields. It is recommended that this register is set during system initialization and remain static.
If the MMU loopback path is enabled for a given requestor, requests will be routed via the L3_MAIN interconnect to the MMU and will again go through the L3 interconnect to the requested physical address. If the MMU loopback path is disabled for a given requestor, those bus requests go directly through the L3_MAIN interconnect to the requested physical address, thus minimizing bus request latency.