Nouveau 3.14 Gets New Acceleration, Still Lacking PM

The Nouveau open-source NVIDIA kernel driver changes for the Linux 3.14 kernel are now known. The Nouveau changes are exciting in having hardware acceleration support for some new GPUs but is less exciting as it's yet another kernel release without proper dynamic power management / re-clocking support.

Merged into David Airlie's drm-next Git branch as the code that will then be sent by the DRM subsystem maintainer into the mainline Linux kernel were the queued up Nouveau changes. The latest work shows this reverse-engineered NVIDIA driver making progress, but still months after NVIDIA pledged support to NVIDIA the biggest downfall of this driver is its inability to proper reclock the GPU.

The Nouveau driver runs the graphics card at whatever core and memory frequencies were programmed at boot. GPUs with Nouveau are thus forced to either run at very low speeds -- for modern hardware with low boot frequencies, in which case the performance is crippling -- or with higher frequencies on older NVIDIA GPUs but with being power inefficient and hot even when the system is idling. For older NVIDIA GeForce GPUs is experimental re-clocking / power management support that's disabled by default and not always reliable while the Kepler/Fermi support is basically non-existent to end-users. Read Nouveau Reclocking: Buggy, But Can Boost Performance for more details along with Nouveau Re-Clocking, NVIDIA vs. Nouveau Drivers.

With the Nouveau DRM driver changes for Linux 3.14 is continued work on the new re-clocking code for Nouveau, but it's not yet ready for end-users and is disabled by default.

Besides working towards power management, there's also acceleration support for the GK110 and GK208 graphics processors. The GK110 is the graphics core that powers the GeForce GTX 780 and GeForce GTX TITAN graphics cards. NVIDIA's GK208 meanwhile is what's found on the low-end GeForce GT 630 and GT 640 graphics cards. With Linux 3.14 is now kernel-side support for these newer graphics processors. These GPUs utilize Nouveau's existing self-generated "chsw" microcode.

Complementing the work towards power management and GK110/GK208 acceleration support are error reporting improvements, overlay improvements, and random other changes. The overlay support includes YUYV support for the NV10 and video overlay support coming for the first time to the old NV04/NV05 hardware. The NV04 was the original Riva TNT and TNT2 graphics cards.

In total this pull request has 12,385 lines of new code while 5,834 lines of code removed. The pull into drm-next for its merging into the mainline Linux kernel in the days ahead can be found here.

This Nouveau 3.14 information rounds out knowing the details already on the Radeon changes, the Intel improvements, and major SVGA2 changes.