I have seen many of my friends complaining about the power button being damaged on Nexus devices and they try not to press it frequently. While that is the case with most Android devices where you need to press the power button often whenever you want the device to wake up, features like sweep to wake or double tap to wake come to your rescue. These features are implemented in the LG G2 by default known as KnockOn but have now been ported to the Nexus 5 too.
Sweep To Wake On Nexus 5 – Demo
Double Tap to Wake On Nexus 5 – Demo
Implementing this feature on Nexus 5 requires a custom kernel and hence an unlocked bootloader. A simple command to unlock the bootloader is fastboot oem unlock. After this, you can flash a CWM image followed by flashing the custom kernel zip via CWM and you’re done.
Though the name of the kernel is bricked kernel, it shouldn’t brick your phone (makes me wonder why is it called so?). The zip file of the kernel can be downloaded from the source link at the end of this post. The source link also provides you with a download link to the zip which helps you uninstall this kernel (or) roll back to the stock kernel.
The double-tap to wake feature works only when you wish to wake up the device and not to lock it back. So you need to use the power button to lock the device back or use various other apps that provide a floating button the screen tapping on which locks the device.
For downloads, visit the original thread on XDA and download the stable version of the kernel.