RemoteFX upper filter tsusbflt.sys breaks USB device enumeration, usbview WDK tool and Device Manager devmgmt.msc RRS feed

  • Question

  • Hi

    I'm not sure if this is the best forum but I'm posting here to start off with a group that will probably understand the issue.

    I'm developing code that needs to enumerate USB devices exactly as the usbview WDK tool does. Exploring my reference PC (Windows 7.1 SP1 all updates applied) with usbview lists the five USB Universal Host Controller but does not enumerate or display any hubs or their attached devices (of which there are many including the mouse and keyboard). All of these devices however work correctly.

    Additionally, looking at any of the USB hubs in Device Manager shows a fault under the "Power" properties tag - there is no display of attached devices and power consumption - only a message: "This hub is not working properly". I have checked all of the drivers and they are standard signed Microsoft.

    Stepping through usbview in VS2012 debug shows that a file open is being attempted against an invalid device so I conclude that there is something wrong with the devices structures or names.

    Comparison with a machine that works correctly shows that in the failing machine the Microsoft upper filter "tsusbflt.sys" is being loaded into the USB Universal Host controller and the USB Root Hub stack above usual drivers such as usbport.sys, usbd.sys and usbhub.sys. This driver is enabled by the RDP RemoteFX capability using the policy editor(see ). I needed this for another part of the development.

    Disabling RemoteFX using the policy editor restores correct operation to usbview, Device Manager and my code. So my question is: is this expected behaviour or is there an issue with RemoteFX and the "tsusbflt.sys" driver?

    Please re-direct my post to a more appropriate forum as necessary.


    Sunday, May 11, 2014 6:14 PM