Double Tap To Wake (screen) - No Such Option?


Why is it so difficult to have the double tap to wake feature? It seems like a very useful function and every phone should have it. What do you think guys?
 
Why is it so difficult to have the double tap to wake feature? It seems like a very useful function and every phone should have it. What do you think guys?
The feature must be activate in kernel code. Should be very easy for Xiaomi but why isn't yet present is a mystere....