Intel Sends Out Initial USB 4.0 Support For The Linux Kernel
Volleyed just a few minutes ago to the Linux kernel mailing list were the initial 22 patches providing the basic USB 4.0 support. USB 4 support in its present form was less than four thousand lines of new kernel code. The bring-up isn't too dramatic and the L.O.C. delta relatively small since USB4 is based on Thunderbolt and thus re-using the kernel's existing Thunderbolt driver code.
It was just last month that the USB 4.0 specification was officially published. USB 4.0 allows two-lane operation on existing Type-C cabling and up to 40 Gbps on certified cables while retaining backwards compatibility with USB3/USB2 and Thunderbolt 3.
With this initial Linux kernel support, there isn't yet USB 4.0 power management support in place as one of the main items left to be accomplished in the near-term. But features like PCIe tunneling, DisplayPort tunneling, USB 3.x tunneling. P2P networking, firmware upgrading, and other fundamentals are in place.
The patches for now are on the LKML. If the review of the code by other upstream developers go well and other bits like power management squared away, it's possible we could see this initial USB 4.0 support submitted for the Linux 5.5 kernel in a few months.