AMD Has A Crucial Linux Optimization Coming To Lower Power Use During Video Playback

There have been ongoing reports from a variety of users and systems around high power use during GPU-accelerated video playback with current-generation AMD Ryzen "Phoenix" laptops. Fortunately, an optimization is coming to benefit Phoenix and forthcoming Strix Point laptops with noticeably lower power consumption during video playback.

AMD engineers have finally been able to root-cause the issue and have provided a fix that enables Dynamic Power Gating during VCN video playback for these latest AMD Ryzen laptop SoCs.

For months there have been bug reports around higher SoC power use under Linux during video playback in particular. In that bug report, prominent AMDGPU Linux maintainer Alex Deucher describes this dynamic power gating functionality as:

"VCN already supports powergating, the patches referenced above just enable it more aggressively (i.e., firmware controlled rather than driver controlled). Firmware can turn it off dynamically between commands while the driver waits for all the currently queued commands to finish before turning it off.

GFX supports both powergating and gfxoff (where the power rail is turned off). Both are already dynamically controlled by firmware. However, for video playback, ideally you would not use GFX at all and just let it stay off.

Firmware also dynamically adjusts the clocks and voltages for both VCN and GFX while they are on based on load."

The patches are now out for review/testing. There are also Git branches available of the VCN dynamic power gating for Linux 6.9 and 6.10 kernels to facilitate in easier testing. Here's to hoping the VCN dynamic power gating will squeeze in as a fix before Linux 6.10 final or make it in early during the Linux 6.11 merge window.