I have an HP Envy laptop on which I have installed Ubuntu 16.04. This model of laptop has 'Swipe Fingerprint Sensor' installed,
Bus 002 Device 004: ID 138a:0050 Validity Sensors, Inc. Swipe Fingerprint Sensor Couldn't open device, some information will be missing. Device Descriptor: bLength: 18 bDescriptorType: 1 bcdUSB: 1.10 bDeviceClass: 255 Vendor Specific Class bDeviceSubClass: 16 bDeviceProtocol: 255 bMaxPacketSize0: 8 idVendor: 0x138a Validity Sensors, Inc. idProduct: 0x0050 Swipe Fingerprint Sensor bcdDevice: 0.60 iManufacturer: 0 iProduct: 0 iSerial: 1 bNumConfigurations: 1
Support for this USB device is very limited but as I don't wish to use it this doesn't matter. However when I use
powertop to monitor power usage I found that this device is using a continuous 4.6 to 5 watts even though it is not in use.
I used the Debian too 'usb-devices' to discover what driver is being used for this device however there doesn't appear to be one loaded:
T: Bus=02 Lev=01 Prnt=01 Port=13 Cnt=01 Dev#= 4 Spd=12 MxCh= 0 D: Ver= 1.10 Cls=ff(vend.) Sub=10 Prot=ff MxPS= 8 #Cfgs= 1 P: Vendor=138a ProdID=0050 Rev=00.60 S: SerialNumber=941442215a3a C: \#Ifs= 1 Cfg#= 1 Atr=a0 MxPwr=100mA I: If#= 0 Alt= 0 #EPs= 4 Cls=ff(vend.) Sub=00 Prot=00 Driver=(none)
So my question is, is there anyway I can disable this device to reduce its power consumption to zero watts? There is a
Autosuspend for unknown USB device 2-14 (138a:0050) in
powertop's Tunable options but this makes no difference to the reported power consumption.
Power est. Usage Events/s Category Description 5.86 W 0.0 pkts/s Device Network interface: eno1 (r8169) 5.15 W 100.0% Device USB device: usb-device-138a-0050 4.17 W 100.0% Device Radio device: btusb