Owners of the LG's Nexus 5 who might have been slightly disappointed not to see the manufacturer's new KnockOn feature may now have a way to get their fix. That is, if they're willing to take the adventure in installing a custom Android kernel on their smartphone.
Although not entirely original, since the Nokia N9 partly featured a similar gesture, the LG G2 debuted with and popularized a gesture that lets a user double tap to wake up the display and, conversely, to put it to sleep. So far, the feature has been the monopoly of LG's most recent premium devices but, as always, there have been attempts by Android developers to bring it to other devices as well.
There currently exists no easy to install app that brings this functionality. Current attempts, such as dt2w (Double Tap 2 Wake) and sweep2wake, all rely on installing and booting from custom kernels. These implementations are, so far, also a bit buggy and consume more power than necessary. Fortunately for Nexus 5 owners, it seems that this feature, or at least one version of it, has been rewritten to work well on the device and without the aforementioned problems. Below is a video demonstrating the feature working on the Nexus 5 thanks to the Bricked-Kernel's sweep2wake implementation.
As you probably noticed, while the waking feature works well, one still has to press the power button to turn the display off again. Also, the feature requires installing a custom kernel, which, in turn, requires a rooted device with an unlocked bootloader. But then again, this is exactly what Nexus devices are made for.