AMD Linux Driver Seeing Support For New Fine Grain Clock Gating Ability

AMD mentioned Fine-Grain Clock Gating as one of the new features for the Radeon RX 6000 series with "Big Navi" but it will also be present with the next-gen Van Gogh APU too. The Linux driver patches for bringing up FGCG are under review.

Fine-Grain Clock Gating was mentioned as part of AMD's work on achieving a ~50% generational performance-per-Watt improvement. This complements the existing AMD Radeon support (and driver coverage) for medium grain clock gating, coarse grain clock gating, and other clock gating features for basically cutting down the GPU power usage to areas of the chip when not in use. With fine-grain clock gating it's sounding like the GPU will be much more aggressive in its handling to conserve every bit of power possible.

Not only is Fine-Grain Clock Gating to be supported by the Radeon RX 6000 series, but the FGCG patches now also confirm it will be supported by Van Gogh APUs too. Since September we've been monitoring AMD's Linux patches around Van Gogh for that next-gen mobile APU with Zen 2 CPU cores and RDNA 2 graphics while supporting DDR5 system memory. That is coming together nicely and should be all mainlined and squared away by the time of seeing AMD Van Gogh notebooks.

There are 3 patches adding the necessary bits for flipping on Fine Grain Clock Gating with GFX10 (Navi) and Van Gogh. This work should land for the Linux 5.11 kernel.