HID Manager callbacks return 0 value for some devices

  • Guys,
    I dont know where to post this problem so I posted it in the USB list
    first but later realized its more of a kernel dev list. My problem is
    that I need to be able to read the mice at the hardware level. I use
    the new HID Manager API for this and the following work (perfectly):

    1. Apple bluetooth mouse (magic mouse)
    2. Apple USB mouse
    3. Logitech USB Mouse
    4. Internal trackpad

    The following give me callbacks with ZERO value (I do get callbacks,
    just has no value):
    1. Apple Bluetooth trackpad (external)
    2. Any mouse attached to a external thunderbolt display

    The code is here. I'm using the newer HID Manager API documented here:

    The code is available at:

    Also if i use the SeizeDevice option:

        IOReturn ret = IOHIDManagerOpen(hidman, kIOHIDOptionsTypeSeizeDevice);

    I can seize ALL devices EXCEPT the trackpad,etc (the ones that give
    back zero value calbacks). Really bizarre. What am I missing with
    these devices?

    Faraz Khan
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