Too many Interrupt events on falling edge

We use interrupts from GPIO in different drivers. Most of them are triggered on falling or any edges.
Our code is very much the same as in your example for iMX6 and VS2005.
The difference is, that we use: L"irqtrig=falling" and L"irqtrig=anyedge"
The problem isnow, that we sporadic receive more than one event for one edge.
I tried it with inmode=Schmitt and different pullups, but success less.
In one case, it was acceptable to use irqtrig=low, to solve it. (The signal source was a ADC Data Ready signal)
In another case, I had to check the GPIO level after each interrupt. This is ok, because the signal duration is always more than 5ms. (The signal source is kind of a mono flop.)
Is there a better way to solve this problem? Maybe with some additional filters? Or is it a bug in the BSP?

Did you check the signal with an oscilloscope? It may be that a slow rising edge or some noise in the signal triggers multiple edges on the same pulse.
On the other side, if I understood correctly, your device generate a pulse that is at least 5ms, since the reaction time of your IST should be much lower (if you configure it to real-time priorities) you can use level-triggered interrupts and avoid checking GPIO state.