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USB Kernel driver

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Wacom devices need a specific kernel driver to claim the tablet. The standard USB HID driver will not expose all features of the tablets and thus the tablet will not work.

Testing Tablet Detection

In this section we will determine which driver, if any, claims control over the tablet. There are at least two drivers that are interested:

  1. (usb)hid.o which may think it is an HID device (for kernel 2.6.17 or older),
  2. the wacom driver which should identify the tablet as its own.

To see which driver is driving the tablet, issuing more /proc/bus/usb/devices should list something similar to the following:

    [jej@ayukawa wacom]$more /proc/bus/usb/devices
    T:  Bus=01 Lev=01 Prnt=01 Port=01 Cnt=02 Dev#=  3 Spd=12  MxCh= 0
    D:  Ver= 1.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs=  1
    P:  Vendor=056a ProdID=0042 Rev= 1.15
    S:  Manufacturer=Tablet
    S:  Product=XD-0608-U
    C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=140mA
    I:  If#= 0 Alt= 0 #EPs= 1 Cls=03(HID  ) Sub=01 Prot=02 Driver=wacom
    E:  Ad=81(I) Atr=03(Int.) MxPS=  10 Ivl=5ms

where Vendor=056a indicates a Wacom device. Driver=wacom means the Wacom driver is in control of the tablet. If you see anything other than wacom after Driver=, your model is not supported in your current kernel and the kernel driver/module wacom.ko needs to be updated. See below.

Alternatively, more /proc/bus/input/devices gives you

    [jej@ayukawa wacom]$more /proc/bus/input/devices
    I: Bus=0003 Vendor=056a Product=0042 Version=1.15
    N: Name="Wacom Intuos2 6x8"
    P: Phys=usb-0000:00:1d.1-2/input0
    H: Handlers=event3
    B: EV=1f
    B: KEY=1cff 0 1f00ff 0 0 0 0 0 0 0 0
    B: REL=100
    B: ABS=f00017b
    B: MSC=1

where, again, Vendor=056a indicates a Wacom device. Name="Wacom Intuos2 6x8" means an Intuos2 6x8 tablet reported to /dev/input/event3. If there is no Wacom after Name=, you need to update the kernel driver. Check if your distribution offers an updated wacom.ko through kernel module backports from upstream kernels or other distribution package. For example Ubuntu users could try Martin Owens' PPA. If no newer wacom.ko is available in your distribution see input-wacom.

On older 2.6 kernel systems, unplug then replug your tablet after issuing tail -f /var/log/messages, you should see a flurry of activity. The exact output depends a lot on your particular kernel and distribution.

   This is Suse 10.2 (2.6.25.20-0.7):
    [jej@ayukawa usb]# tail /var/log/messages
    usb 2-2: USB disconnect, address 2
    usb 2-2: new full speed USB device using uhci_hcd and address 3
    usb 2-2: configuration #1 chosen from 1 choice
    input: Wacom Intuos4 6x9 as /devices/pci0000:00/0000:00:1f.4/usb2/2-2/2-2:1.0/input/input8
    usb 2-2: New USB device found, idVendor=056a, idProduct=00b9
    usb 2-2: New USB device strings: Mfr=1, Product=2, SerialNumber=0
    usb 2-2: Product: PTK-640
    usb 2-2: Manufacturer: Tablet

If all went well like above, the USB device was successfully detected and handled by the wacom driver. This presumably means that information like pressure and tilt will be received on /dev/input/event3.

If instead you got any of the following lines in your log, the wacom driver did not get control. Either your wacom kernel driver doesn't support your tablet or hid is in control.

    	input0,hiddev0: USB HID v1.00 Mouse [Tablet PTK-640] on usb1:5.0
    	input0: Tablet PTK-640 on usb1:5.0

To check the event stream coming from the kernel, see Analysing kernel events

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