CPU idle PM support

modulename: cpuidle.ko

configname: CONFIG_CPU_IDLE

Linux Kernel Configuration
└─>Power management and ACPI options
└─>CPU Idle
└─>CPU idle PM support
In linux kernel since version 3.10 (release Date: 2013-06-30)  
CPU idle is a generic framework for supporting software-controlled
idle processor power management. It includes modular cross-platform
governors that can be swapped during runtime.

If you're using an ACPI-enabled platform, you should say Y here.

source code:
arch/arm/mach-tegra/cpuidle.c