I use lsinput to display mouse device on a device. The mouse related entry is
/dev/input/event2
bustype : BUS_USB
vendor : 0x413c
product : 0x301a
version : 273
name : "PixArt Dell MS116 USB Optical Mo"
phys : "usb-ff540000.usb-1.1/input0"
uniq : ""
bits ev : (null) (null) (null) (null)
Why values in bits ev entry are all null?
The bits aren’t really null, each (null) corresponds to a bit set in the descriptor, but for which lsinput doesn’t have a name. lsinput doesn’t have a name because its build process extracts names from a kernel-provided header file, which changed a while ago in a way which broke the lsinput build process.
If you build the latest release, you’ll be able to see the bit names again:
$ wget https://www.kraxel.org/releases/input/input-1.3.tar.gz
$ tar xf input-1.3.tar.gz
$ cd input-1.3
$ make
$ ./lsinput -v
(assuming you have everything needed for the build, basically a C compiler and make).
