On Tue, Oct 31, 2017 at 2:16 PM, Andrew Lunn [off-list ref] wrote:

quoted

The discussion here is interesting, it is customary for GPIO drivers
to implement double-edge detection emulation by swapping the
edge detector around like this.

Hi Linus

I was not aware this was customary.

quoted

It might be possible to collect some generic information about
this in the Documentation/gpio/driver.txt document.

Yes, i think it should be documented somewhere. Even in the use case
here, detecting an SD card being inserted/removed, you could get some
bounce on the microswitch, miss an edge, and be in the wrong state.

Indeed :/

This is I guess why it is a good idea to combine this with the
debounce feature if the hardware supports it.

I'll think about some writeup.

Yours,
Linus Walleij