SPRUIU1C July 2020 – February 2024 DRA821U , DRA821U-Q1
As per PCIe Base Specifications, Root Port ports only receive interrupts. There is no mechanism to generate interrupts from RP port to EP mode as per PCIe specification.
However, PCIe subsystem does support generation of interrupts from RP to EP. The downstream interrupts described in Section 12.2.3.4.4.3.1, PCIe Core Downstream Interrupts provides a mechanism for the RP to generate software triggered interrupts to the EP.