1

I have one USB touchscreen connected to my hardware setup but using cat /proc/bus/input/devices gives me two entries for the same device :

I: Bus=0003 Vendor=2965 Product=5023 Version=0110
N: Name="Kortek Kortek Touch"
P: Phys=usb-0000:00:14.0-3.4/input2
S: Sysfs=/devices/pci0000:00/0000:00:14.0/usb3/3-3/3-3.4/3-3.4:1.2/0003:2965:5023.0006/input/input7
U: Uniq=S20131028
H: Handlers=mouse1 event7 js0
B: PROP=0
B: EV=1b
B: KEY=30000 0 0 0 0 0 0 0 0
B: ABS=3
B: MSC=10


I: Bus=0003 Vendor=2965 Product=5023 Version=0110
N: Name="Kortek Kortek Touch"
P: Phys=usb-0000:00:14.0-3.4/input0
S: Sysfs=/devices/pci0000:00/0000:00:14.0/usb3/3-3/3-3.4/3-3.4:1.0/0003:2965:5023.0004/input/input13
U: Uniq=S20131028
H: Handlers=mouse2 event13
B: PROP=2
B: EV=b
B: KEY=400 0 0 0 0 0 0 0 0 0 0
B: ABS=a608000 3

why are there two different entries for this same device ?

  • @JdeBP the OP has a point. This isn't cross-posted, the question on SO is asking something different. – terdon Jul 8 '16 at 16:41
1

I think I found the reason behind this.

The same device is exposed to USB subsystem as two devices with different interfaces.

like in the entry Sysfs=/devices/pci0000:00/0000:00:14.0/usb3/3-3/3-3.4/3-3.4:1.2/0003:2965:5023.0006/input/input7, the device exposes Interface 2 of the hardware as seen from the string 3-3.4:1.2 where the last digit is InterfaceNumber.

If we look at the output of cat /sys/devices/pci0000:00/0000:00:14.0/usb3/3-3/3-3.4/3-3.4:1.2/0003:2965:5023.0006/input/input7/device, we can see that DRIVER=hid-generic which says that this interface of the hardware exposes this device as USBHID generic.

However, for the other entry whose interface is 0 as seen in /devices/pci0000:00/0000:00:14.0/usb3/3-3/3-3.4/3-3.4:1.0/0003:2965:5023.0004/input/input13 , the output of cat /sys/devices/pci0000:00/0000:00:14.0/usb3/3-3/3-3.4/3-3.4:1.0/0003:2965:5023.0004/input/input13/device shows that DRIVER=hid-multitouch which means that this interface of the hardware exposes it as HID MULTITOUCH.

Therefore, the two entries for the same hardware.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.