I've encountered a weird problem and I'm not sure whether it's actually a problem or everything's ok.
But going straight to the point. I've got Raspberry Pi Zero W, one of its pins is configured as GPIO IN, with interrupt triggered when falling edge is detected. GPIO has attached external, hardware pull-up 10K.
The interrupt is handled in my kernel driver, also I've been using one of the debouncing techniques that uses jiffies. And it seemingly looks ok, but there is actually one problem - I don't have to ground the pin in order to cause the interrupt.
I can take one of my multimeter's probes and touch the pin and then an interrupt occurs. Is it normal? Shouldn't it be a little bit less sensitive? Shouldn't the interrupt be triggered when pin's state changes to 0 (when I ground it)?
I also tried to use an RC filter but it didn't help.