Linux 3.7 May Help Radeon Users With Power

While the main DRM pull request for the Linux 3.7 kernel has yet to be submitted to Linus Torvalds, the Radeon DRM pull for the Linux 3.7 was just sent into David Airlie as the DRM sub-system maintainer.

The Linux 3.7 kernel offers the following highlights as explained by Alex Deucher in this email:

- Asynchronous VM page table updates for Cayman/SI
- 2 level VM page table support. Saves memory compared to 1 level page tables.
- Reworked PLL handing in the display code allows lots more combinations of monitors to work, including more than two DP displays assuming compatible clocks across shared PLLs. This also allows us to power down extra PLLs when we can share a single one across multiple displays which saves power.
- Native backlight control on ATOMBIOS systems.
- Improved ACPI support for interacting with the GPU. Fixes backlight control on some laptops.
- Document AMD ACPI interfaces
- Lots of code cleanup
- Bug fixes

What may excite some users of the open-source Radeon driver is the modest work done in the area of power management. The reworked PLL handling can now power down extra PLLS, there's native backlight control for AtomBIOS systems, and improved ACPI support for GPU interaction. For those wishing to take the power support further, the AMD ACPI interfaces in the Radeon DRM driver are now documented. There's a net gain of two thousand lines of code for Radeon 3.7 compared to Radeon 3.6.

Aside from the open-source driver graphics performance and lack of accelerated video support, power management seems to be one of the other most frequently criticized items.