AMD Preparing More Linux Improvements Around USB4/Thunderbolt

As part of AMD Rembrandt APUs having USB4 support with that specification based on the Thunderbolt 3 protocol, AMD in recent months has been making a number of Linux driver improvements to enhance the USB4/Thunderbolt support for their platforms.

AMD patch series in recent times have included USB4 DisplayPort Tunneling and other USB4/Thunderbolt work. Their latest is refactoring various Linux kernel around an "is_thunderbolt" check used by drivers within their kernel for altering their behavior if the device is connected via Thunderbolt as opposed directly via PCIe and as a means of determining if the device is potentially removable / externally connected. That is_thunderbolt check started out for early Intel Thunderbolt controllers that lacked command completed events.

AMD Linux engineer Mario Limonciello has been posting a few revisions of the "is_thunderbolt" patch series this past week so that ultimately the intended driver behavior covers "non-Intel USB4 designs" (a.k.a. AMD). The is_thunderbolt check is now treated as a kernel quirk and various other Thunderbolt-related kernel code changes are also part of the proposed patch series. As part of the 12 patches is also cleaning up AMD and Nouveau driver code for its paths involving eGPU / removable GPU support and other quirks.

See this patch series for more details but long story short AMD is working on more USB4/Thunderbolt handling improvements for Linux to improve non-Intel platforms.

USB4 on the AMD side is being introduced with the Ryzen 6000 mobile series APUs.