"Ghost" inputs with usb encoder?

[WeirdH]

I have a 2-player arcade cab with sticks and buttons going into two generic dragonrise usb encoders. The encoders connect up to my Pi3B+. Everything works as expected, but for one minor niggle: sometimes the Emulationstation screensaver (slideshow) stops on its own.

After some googling around, I ran evtest, because I had read something about ghost inputs. Note that controlling games or navigating gamelists in ES always works fine, so calling it ghost inputs might even be incorrect.

evtest correctly detects two dragonrise encoders and one Logitech keyboard (I have no bluetooth connections, although the keyboard has its own usb dongle). The keyboard expectedly only registers inputs when I strike a key, but both usb encoders show a constantly scrolling list, as if they are always giving input.

Is this expected behaviour or is there something wrong with my sticks/encoders? And if so, is there a fix?

EDIT: jstest does not report constant inputs btw. Which one can I trust?

[mitu]

@WeirdH said in "Ghost" inputs with usb encoder?:

The keyboard expectedly only registers inputs when I strike a key, but both usb encoders show a constantly scrolling list, as if they are always giving input.

What kind of events ? Some controllers (like the PS 4 Dualshock) have an accelerometer/mouse included which generates constantly events, since the OS is polling it for changes all the time. They' don't show with jstest because no change is detected, but they're shown by evtest.

[WeirdH]

@mitu It says over and over, after a timestamp

type 3 (EV_ABS), code 2 (ABS_Z), value 130
-------------- SYN-REPORT--------------

And during scrolling, the value seems to alternate between everything from 130 to 137.

[mitu]

@WeirdH That looks ok, doesn't indicate any 'ghost' inputs.

[WeirdH]

@mitu Cool, thanks! That puts my mind at ease.