Better power management for Radeon driver in Linux
AMD developer Alex Deucher has published a patch series, consisting of 165 changes, that significantly improves support for the runtime power management features in the Linux kernel's Radeon driver. With the patches, the driver can now handle not only AMD's DPM (Dynamic Power Management) but also ASPM (Active State Power Management, used on PCIe devices) for several series, from the R600 family to the Southern Islands, which are used by the Radeon HD models 2400 to 7970 and some models from the 8000 family.
The patches also provide support for the CIK graphics chips in the Sea Islands family; graphics cards with those GPUs – apparently referred to in-house as Bonaire, Kaveri and Kabini – could be on the market later this year, if the rumours are true. The entire patch series should be included in Linux 3.11, which is planned for September.
With this improved support for power management, just under six years since AMD first started actively participating in open source graphics driver development, the developers have now taken care of the last big feature gap in the open source graphics drivers for Radeon graphics cores. Another long-time feature gap was a lack of support for UVD, the video accelerator that can be used in the Mesa 3D development branch and the release candidates for the Linux 3.10 kernel, the final version of which should be out soon. But there's certainly still room for improvement – AMD's proprietary Catalyst graphics driver for Linux, for example, can in some cases tease out much better 3D performance, especially from the newer Radeon graphics cores.