Hi, I'm writing button driver. The button is based on GPIO.When the button is pressed or released, the interrupt is generated. According to the GPIO value(1 or 0) , I can know which action is taken(pressed or released). However, a question occurred to me. Do I need to consider when to get the GPIO value? I mean is it possible that GPIO value will be changed caused by another interrupt when I get the GPIO value in top or bottom half of first interrupt? I know the CPU is fast and pushing/releasing button is slow, so it should not happen in practice. But let's just consider this case in theory. You can assume the button is pushed or released very very fast. Seems that GPIO interrupt is special comparing with other device with cache. There is no cache to store data(GPIO value) for GPIO. Right? Can someone help to clarify this question? Thanks a lot. Tony