ACPI Power Management Gets Improved In Linux 3.8

The ACPI and power management updates targeting the Linux 3.8 kernel were already submitted to Linus Torvalds this morning. There's a whole lot of new work to look forward to when it comes to power management in this next kernel.

From the 3.8 pull request for ACPI by Rafael J. Wysocki, the highlights include:

- Introduction of device PM QoS flags allowing kernel subsystems and user space to constraint the selection of device low-power states by adding binary requirements (like whether or not it is allowed to remove power from the given device entirely).

- ACPI device power management update allowing subsystems other than PCI to use ACPI device PM more easily.

- ACPI device enumeration rework allowing additional kinds of devices (platform, SPI, I2C) to be enumerated via ACPI in analogy with the enumeration based on Device Trees. From Mika Westerberg, Adrian Hunter, Mathias Nyman, Andy Shevchenko, and yours truly.

- ACPICA update to version 20121018. Fixes bugs, adds some new ACPI 5 features, cleans up some things and removes some differences between the kernel's ACPICA code and the upstream. From Bob Moore and Lv Zheng.

- ACPI memory hotplug update from Wen Congyang and Yasuaki Ishimatsu.

- Introduction of acpi_handle_() messaging macros and ACPI-based CPU hot-remove support from Toshi Kani.

- ACPI EC updates from Feng Tang.

- cpufreq updates from Viresh Kumar, Fabio Baltieri and others.

- cpuidle changes to quickly notice governor prediction failure from Youquan Song.

- Support for using multiple cpuidle drivers at the same time and cpuidle cleanups from Daniel Lezcano.

- devfreq updates from Nishanth Menon and others.

- cpupower update from Thomas Renninger (Thomas is going to maintain that tool going forward).

- Fixes and small cleanups all over the place.