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Problems with mixed USB Versions (1.1and 2.0) on one single USB hub

This document (3671067) is provided subject to the disclaimer at the end of this document.

Environment

Novell Linux Point of Service 9 SSP3 (Supplemental Support Pack 3)
Novell Linux Desktop 9 SP3 (Service Pack 3)
SUSE Linux Enterprise Server 9 SP3 (Service Pack 3)
SUSE Linux Enterprise Point of Service 10
SUSE Linux Enterprise Point of Service 11

Situation

There are sometimes sporadic timeouts if mixed USB 2.0 and USB 1.1 devices are plugged in on one single USB hub.


Resolution

To avoid this problem all devices have to run at USB High Speed (USB 1.1).This can be done by unloading the EHCI driver module:

modprobe -r ehci_hcd

The following steps are necessary to permanently disable the EHCI driver module after reboot:
  1. Execute:
    echo "/sbin/rmmod ehci_hcd">> /etc/init.d/boot.local
  2. Execute:
    echo "install ehci_hcd /bin/true">> /etc/modprobe.conf.local

Additional information for SLEPOS10 and 11

While the above is a necessity on NLPOS9, on SLEPOS 10 and 11 the situation has improved.
The vast majority of devices are working, only a few still need to be run on high speed only.
Only in case a USB device causes trouble, mount the image loopback to e.g. /mnt and run the  commands:


  1. echo "/sbin/rmmod ehci_hcd">> /mnt/etc/init.d/boot.local
  2. echo "install ehci_hcd /bin/true">> /mnt/etc/modprobe.conf.local
Instead of modprobe.conf.local it's also feasible to use a file  , e.g. 90-disable-ehci_hcd.conf below /etc/modprobe.d/

unmount the image and reboot the cash register.

Additional Information

Please note:
Using an external USB 2.0capable hub with only USB 1.1 devices plugged into itcould also cause problems.
External hubs send all signals from the USB 1.1 devices into an USB 2.0 stream. This means, there is also a mixed environment on the system.
Unloading the EHCI driver is also necessary.

Disclaimer

This Support Knowledgebase provides a valuable tool for NetIQ/Novell/SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:3671067
  • Creation Date:23-MAY-07
  • Modified Date:30-APR-12
    • SUSESUSE Linux Enterprise Point of Service
      SUSE Linux Enterprise Server

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