我最近安装了 Ubuntu 16.04，从那时起，我的 USB 2.0 端口都无法正常工作，但我的 USB 3.0 端口可以正常工作（前后）。在我之前的 Fedora 安装中，所有端口都可以正常工作。我插入的设备都是低功耗的：一个鼠标接收器、一个网络摄像头和一个麦克风。
主板：技嘉990FXA-UD3
$ dmidecode
Handle 0x0012, DMI type 8, 9 bytes
Port Connector Information
Internal Reference Designator: J3A1
Internal Connector Type: None
External Reference Designator: USB1
External Connector Type: Access Bus (USB)
Port Type: USB
Handle 0x0013, DMI type 8, 9 bytes
Port Connector Information
Internal Reference Designator: J3A1
Internal Connector Type: None
External Reference Designator: USB2
External Connector Type: Access Bus (USB)
Port Type: USB
Handle 0x0014, DMI type 8, 9 bytes
Port Connector Information
Internal Reference Designator: J3A1
Internal Connector Type: None
External Reference Designator: USB3
External Connector Type: Access Bus (USB)
Port Type: USB
$ lspci
00:12.0 USB controller: Advanced Micro Devices, Inc. [AMD/ATI] SB7x0/SB8x0/SB9x0 USB OHCI0 Controller
00:12.2 USB controller: Advanced Micro Devices, Inc. [AMD/ATI] SB7x0/SB8x0/SB9x0 USB EHCI Controller
00:13.0 USB controller: Advanced Micro Devices, Inc. [AMD/ATI] SB7x0/SB8x0/SB9x0 USB OHCI0 Controller
00:13.2 USB controller: Advanced Micro Devices, Inc. [AMD/ATI] SB7x0/SB8x0/SB9x0 USB EHCI Controller
00:14.5 USB controller: Advanced Micro Devices, Inc. [AMD/ATI] SB7x0/SB8x0/SB9x0 USB OHCI2 Controller
00:16.0 USB controller: Advanced Micro Devices, Inc. [AMD/ATI] SB7x0/SB8x0/SB9x0 USB OHCI0 Controller
00:16.2 USB controller: Advanced Micro Devices, Inc. [AMD/ATI] SB7x0/SB8x0/SB9x0 USB EHCI Controller