PCI and PCIe
This is a very huge topic spanning 6 generations of specifications (and PCIe 7 has just arrived). Luckily it doesn't take that much effort to start understanding output of lspci.
References
Videos
- Overview of PCI(e) Subsystem - Kishon Vijay Abraham, Texas Instruments
- Writing a virtual PCI device + driver from scratch in 2 hours and 23 seconds
- Some of the videos in Arch4001 (playlist)
- Linux PCI(e) Driver Tutorial (playlist)
- GNU/Linux & PCI (Express) (playlist)
- LIS25 207 How not to write PCIe controller drivers in Linux Kernel