Linux Now Has Audio Run-Time Power Management

The sound pull request for the Linux 3.7 kernel was finally sent in today and it provides a few new features for the Linux kernel audio drivers, including run-time power savings support.

SUSE's Takashi Iwai sent in the pull request this morning as the sound/ALSA driver maintainer but came in a bit late due to holidays. Highlights for the sound update in Linux 3.7 consist of:

- Most of the kernel audio drivers now hook into the new power management API call-backs.

- The very common HD audio controller Linux driver now has support for run-time power management (PM) and support of D3 clock-stop. This power saving support at run-time can also be toggled via the power_save option over sysfs.

- The HD audio driver also had its firmware loading code rewritten.

- Various ASoC driver changes.

- New drivers for Wolfson Microelectronics Bells, Wolfson Microelectronics WM0010, and DA9055. The ux500 and wm2000 sound drivers were also called out for being enhanced.

The ALSA HDA driver run-time power management support allows for additional power savings by allowing the controller to be suspend and its parent device can now also be suspended. The PCI sub-system is able to choose the lowest power state possible for the controller. For ACPI PM systems this means that the D3cold state is now possible.

The Linux 3.7 sound pull request can be seen on the kernel mailing list. This sound update is just one of many exciting features for the Linux 3.7 kernel.