Following the kernel developers' addition of a driver to the kernel supporting the ACPI Integrated Graphics Device OpRegion Specification, as we reported previously, thanks to ACPI developers, a change to the driver found its way into the kernel on Wednesday night. The modification tells the driver to give preference to ACPI for controlling backlighting in notebook displays. Netbook and notebook drivers for Asus – 1, 2, Compal, Fujitsu, MSI, Sony and IBM/Lenovo now no longer control brightness if it can be handled by ACPI. These two processes sometimes butted heads in the past.

During the merge window, kernel hackers had already incorporated the panasonic-laptop driver for Let's Note series Panasonic laptops that allows display brightness to be adjusted and activates previously useless function keys. The Toshiba notebook driver can now toggle Bluetooth on and off using the rfkill framework.

Range hrtimers reduce CPU power consumption, increasing battery life for notebooks. They allow the kernel to perform tasks, which can be run a few fractions of a second earlier or later, sometime within a specified time window. That makes it easier for the kernel to bundle several tasks and perform them in one fell swoop, lengthening the time in which the CPU operates in the power-saving sleep mode; that makes it possible to switch to yet deeper CPU sleep modes that save even more power – see also, LWN.net article on range hrtimers.

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