USB Updates In Linux 5.5 Help Intel Ice Lake, NVIDIA Xavier + More - But No USB 4.0 Yet

Written by Michael Larabel in Hardware on 29 November 2019 at 03:00 PM EST. 6 Comments
Earlier this week as part of his series of pull requests, Greg Kroah-Hartman has submitted the USB subsystem updates for the in-development Linux 5.5 kernel.

Among the USB changes for this next kernel release, which will debut as stable in early 2020, include:

- Various improvements to the USB Type-C port manager code.

- XHCI mainline support for the NVIDIA Tegra194 (Xavier) SoC.

- Various code clean-ups to the longstanding USB Lego Infrared Tower driver.

- The mainline kernel is disabling UAS for JMicron SATA enclosures. There have been out-of-tree patches for years and bug reports around JMicron SATA enclosures with incorrect block sizes or other alignment issues. Disabling USB Attached SCSI (UAS) should workaround these JMicron problems. Merged is the four year old patch that's been carried in distribution kernels and elsewhere while now finally landed.

- Allowing host run-time power management for Intel Ice Lake xHCI as another Ice Lake power optimization.

- Various other USB driver updates, gadget driver improvements, and code clean-ups in the USB area of the kernel.

The complete list of USB changes can be found via this pull request.

Not found in Linux 5.5 is USB 4.0 support. While the USB 4.0 specification was finalized just in September, already last month Intel posted initial USB 4.0 Linux kernel driver patches. The quick turnaround is in large part due to USB 4.0 being based on Thunderbolt. The USB 4.0 Linux patches continue to be worked on by Intel engineers and others but just not ready in time for Linux 5.5. With USB 4.0 devices not expected until late 2020, there still is plenty of time ahead for the Linux support to settle down.
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