USB port power off Kernel/Userspace API

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The Intel Lynx Point chipset includes a new power savings mechanism that allows software to turn off the USB port power (VBUS) via an ACPI call. This mechanism is designed to save power on unused internal USB ports, but it could be used to save power on external ports or even simulate a physical disconnect for misbehaving USB devices. This presentation will provide background on the mechanism, before opening the floor to discussion on what sort of API the kernel should provide userspace to power down ports, and how userspace could use this API to save power, while not confusing the user with "dead" USB ports. Target audience: kernel developers working with USB device drivers, userspace developers for applications that touch USB devices (e.g. libusb, ModemManager, ConnMan), and desktop developers for Gnome, KDE, XFCE, etc.


Sarah Sharp is the xHCI driver maintainer. She has been adding USB 3.0 support to the Linux kernel for the past five years. Sarah works in Intel's Open Source Technology Center, along with Tianyu Lan. Tianyu ([HTML_REMOVED]) is a Linux kernel ACPI developer, and is the author of the patchset for the port power off mechanism.