This video explains the following in the PCIe Protocols
Introduction to PCIe Protocols
Concepts like lane, link, initialization, differential signal, throughput.
PCIe Topology, various components ( Root Complex, End Point ( Legacy End point, Native End Point), Switch etc.
PCIe architecture in terms of logical layers.
Three layers ( transaction layer, link layer and Physical layer).
Task of each layer
Logical Packet flow inside PCIe controller