Nouveau Patches: Kepler GDDR5 Re-Clocking, PCI-E Speed Changes & More

Written by Michael Larabel in Nouveau on 13 October 2015 at 11:23 AM EDT. 2 Comments
Last month I wrote about an experimental Nouveau code branch that offered better GDDR5 Kepler re-clocking support. For some, this branch allows Nouveau users to finally fully re-clock their GeForce GTX 600/700 series graphics cards. Those patches are now being offered up for mainline Nouveau.

Karol Herbst was the developer that had been working on this GDDR5 Kepler re-clocking support for Nouveau where users have been reporting good results. Yesterday he mailed out the patches for fixing the GDDR5 re-clocking on Kepler GPUs, "this patch fixes one of the more serious issues while reclocking gddr5 on kepler cards. It works for me and for a bunch of others I met on IRC." The patch fixes a PLL instability affecting graphics cards with GDDR5 video memory and is just about one hundred lines of changed code.

Karol Herbst also sent out nine patches for PCI Express speed change support on GPUs going back to the Tesla while supporting up through Fermi and Kepler. This new big code addition is for properly raising the PCI Express link speed for the hardware, which the Nouveau driver previously didn't cover and should also boost the performance at least for bandwidth-limited cases.

He also sent out another patch series for moving the pstate handling code from sysfs over to debugfs.

Hopefully this code can be quickly tested and reviewed, where ideally we could end up seeing the GDDR5 re-clocking and PCI-E link speed improvements in Nouveau for Linux 4.4. The Nouveau DRM code has already started collecting other improvements for Linux 4.4.
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Michael Larabel is the principal author of and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via

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