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I recently installed Ubuntu on my computer on a separate (internal) hard drive from Windows, and everything works fine except it will not recognize devices plugged into the rear USB ports on my computer. Only the front ones work. I tried looking into power control, and I disabled auto-suspend for all of the USB ports, but it still does not work. When I run

cat /sys/bus/usb/devices/usb*/power/control

it returns everything as "on." I then tried un-plugging my devices, running

tail -f /var/log/syslog

and plugging them back in to see what the error is, and I saw the following errors for each device:

device not accepting address x, error -32
unable to enumerate USB device on port x

When I boot into Windows, I do not have any of these problems, and the keyboard and mouse I have plugged into the rear ports work in the BIOS and on the purple Ubuntu screen that asks which OS to boot. They only stop working once the login screen appears. Please help! Thank you

Edit here are my hardware specifications:

  • Mouse and keyboard that are not working are stock Dell devices.
  • Ubuntu is running on a 120GB SSD, and Windows is on a 256 GB SSD.
  • CPU is an AMD FX-6300
  • Motherboard is a Gigabyte GA-970A-DS3P
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    Thank you. As expected, a motherboard with a "broken IOMMU". Either follow the additional instructions posted here askubuntu.com/a/884608/589808 (the iommu=soft part, of course, not the nomodeset) or simply install 16.10 instead (the 4.8 kernel includes a workaround for your hardware).
    – user589808
    Feb 26, 2017 at 18:38
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    I updated to 16.10 and now my devices do not work with the front ports either. I have no way to interact with my computer on Ubuntu anymore.
    – Cooper Johnston b0gosort
    Feb 26, 2017 at 21:04
  • Have you tried the Grub parameter?
    – user589808
    Feb 26, 2017 at 21:13
  • I cannot use Ubuntu at all anymore since none of the ports work.
    – Cooper Johnston b0gosort
    Feb 26, 2017 at 21:23
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    You CAN always use them in Grub menu (unless you somehow disabled something at UEFI) because the issue occurs only after loading the graphical desktop. Please don't come here again just to say "it doesn't work" because I've installed Ubuntu in dozens of similar motherboards so, unlike you, I know what I'm talking about.
    – user589808
    Feb 26, 2017 at 21:32

1 Answer 1

Reset to default
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So I found the answer was go go into terminal and type

sudo -H gedit /etc/default/grub

Then in the file I added iommu=soft between the "" in the GRUB_CMDLINE_LINUX= line and restarted my computer.

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