The u-blox-C027 is a complete starter kit that allows quick prototyping of a variety of applications for the Internet of Things. The application board has a MAX-M8Q GPS/GNSS receiver and ...

Running Ublox C027 with Linux Mint 13 or Ubuntu 12.4 on a USB 3.0 port.

14 Feb 2014

To anyone having intermittent problems on Linux and connecting mbed and/or Ublox C027

This page is to help anyone who notices issues in the drive becoming unresponsive or not being identified as a USB mass storage device.

If you find that when inserting the device into the USB port it does not get identified as a mass storage device and other devices refuse to work after using the mbed it might be your machine!

Open a terminal on your linux box and use demessage to find any errors being pushed out by the kernel.

dmesg usb error

[ 4437.454187] usb 3-2: USB disconnect, device number 6
[ 4437.454299] sd 9:0:0:0: Device offlined - not ready after error recovery
[ 4437.458709] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called with disabled ep ffff8800c0f5e340
[ 4437.458712] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called with disabled ep ffff8800c0f5e300
[ 4437.458715] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called with disabled ep ffff8800c0f5efc0
[ 4437.458717] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called with disabled ep ffff8800c0f5ef80
[ 4437.458720] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called with disabled ep ffff880036579ac0
[ 4437.458722] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called with disabled ep ffff8800c0f5ee80
[ 4437.458725] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called with disabled ep ffff8800c0f5eec0
[ 4437.459093] xhci_hcd 0000:00:14.0: ERROR no room on ep ring
[ 4437.459096] xhci_hcd 0000:00:14.0: ERR: No room for command on command ring
[ 4437.459102] xhci_hcd 0000:00:14.0: ERROR no room on ep ring
[ 4437.459103] xhci_hcd 0000:00:14.0: ERR: No room for command on command ring
[ 4437.459106] hub 3-0:1.0: couldn't allocate port 2 usb_device
[ 4487.109908] xhci_hcd 0000:00:14.0: ERROR no room on ep ring
[ 4487.109919] xhci_hcd 0000:00:14.0: ERR: No room for command on command ring
[ 4487.109926] hub 3-0:1.0: couldn't allocate port 2 usb_device
[ 4523.498801] xhci_hcd 0000:00:14.0: ERROR no room on ep ring
[ 4523.498805] xhci_hcd 0000:00:14.0: ERR: No room for command on command ring
[ 4523.498807] hub 3-0:1.0: couldn't allocate port 2 usb_device
[ 4541.567497] xhci_hcd 0000:00:14.0: ERROR no room on ep ring
[ 4541.567501] xhci_hcd 0000:00:14.0: ERR: No room for command on command ring
[ 4541.567504] hub 3-0:1.0: couldn't allocate port 2 usb_device
[ 7328.568877] xhci_hcd 0000:00:14.0: ERROR no room on ep ring
[ 7328.568881] xhci_hcd 0000:00:14.0: ERR: No room for command on command ring
[ 7328.568884] hub 3-0:1.0: couldn't allocate port 2 usb_device
[ 7784.115352] xhci_hcd 0000:00:14.0: ERROR no room on ep ring
[ 7784.115357] xhci_hcd 0000:00:14.0: ERR: No room for command on command ring
[ 7784.115360] hub 3-0:1.0: couldn't allocate port 2 usb_device
[ 8227.026105] xhci_hcd 0000:00:14.0: ERROR no room on ep ring
[ 8227.026116] xhci_hcd 0000:00:14.0: ERR: No room for command on command ring
[ 8227.026124] hub 3-0:1.0: couldn't allocate port 2 usb_device

Notice the HCI error "No room for command on command ring". This seems to be an issue with the Linux Kernel on some machines when using a USB 3.0 port. To find out what version of Linux you are using use:

Linux Version

~ $ cat /etc/*-release
DISTRIB_ID=LinuxMint
DISTRIB_RELEASE=13
DISTRIB_CODENAME=maya
DISTRIB_DESCRIPTION="Linux Mint 13 Maya"
NAME="Ubuntu"
VERSION="12.04.4 LTS, Precise Pangolin"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu precise (12.04.4 LTS)"
VERSION_ID="12.04"

Bug has been reported here: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1155002 And here: http://askubuntu.com/questions/187644/error-no-room-on-ep-ring-with-usb-3-0-device

I hope this helps someone and saves hours of work!

19 Feb 2014

To anyone who has this problem this is how you can upgrade your kernel to 3.4 which hopefully fixes the USB 3.0 bug on Linux kernels <3.2.

Upgrading Your Kernel to 3.4


/>     mkdir  ~/Desktop/precise-kernel-3.4
/>     cd  Desktop/precise-kernel-3.4/
/>     wget http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.4-precise/linux-headers-3.4.0-030400-generic_3.4.0-030400.201205210521_amd64.deb
/>     wget http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.4-precise/linux-image-3.4.0-030400-generic_3.4.0-030400.201205210521_amd64.deb
/>     wget http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.4-precise/linux-headers-3.4.0-030400_3.4.0-030400.201205210521_all.deb
/>     sudo dpkg -i *.deb

You will need to reboot your machine. To check that you now have an upgraded kernel just do: /> uname -a

Should show something like this:

Check Your Kernel

/>     uname -a
/>     Linux nherriot-Zenbook 3.4.0-030400-generic #201205210521 SMP Mon May 21 09:22:02 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

Kind regards, Nicholas.