Type-0 or type-1 configuration transactions are generated when operating as Root Port to enumerate the PCIe hierarchy. The following summarizes when a type-0 or a type-1 configuration transaction is generated. The bus, device and function number terminology used in the following description is extracted from the incoming AXI address hitting the ECAM aperture.
•When the bus number in the ECAM address == PCIe core bus number.
°For device number = 0 and function number = 0, an internal configuration access is generated for the integrated block for PCIe.
°If either device number or function number is non-zero, transaction is ended with a DECERR.
•If the target bus number in an ECAM address == secondary bus number programmed through CSR module.
°For device number = 0, a type-0 configuration TLP is transmitted.
°For non-zero device number, the transaction is ended with DECERR.
•When an ECAM address targets a bus number that is different from the other options, a type-1 configuration TLP is transmitted.