AMD launched FreeSync Panel Replay: New Linux technology to reduce power consumption

AMD launched FreeSync Panel Replay: New Linux technology to reduce power consumption when the screen is still

AMD launched FreeSync Panel Replay: New Linux technology to reduce power consumption when the screen is still.

AMD has released a series of patches that add a new feature to the display code “DC” of its AMDGPU Linux kernel graphics driver: FreeSync Panel Replay.

Targeted at AMD Ryzen laptops with DCN v3.1.4 tiles or newer, this feature reduces power consumption when the screen content is unchanged.

Currently, modern laptops already have power-saving technologies like panel self-refresh (PSR), which reduces power consumption when the screen content is static.

But FreeSync Panel Replay is a new technology, it can only be used on Display Core Next 3.1.4 + hardware, and it cannot be activated at the same time as PSR.

AMD believes this new feature is superior to PSR because it keeps the source and sink in sync, resulting in lower latency when exiting modes, can handle more usage scenarios, and makes it easier to control the refresh rate of the sink.

AMD describes FreeSync Panel Replay in the patch notes:

In some cases, the GPU repeatedly sends the same frame to the receiver without any updates or changes. These repeated transfers are wasteful and cause power consumption in different aspects of the system:

1. DCN obtains a frame of data from DF/UMC/DRAM. This memory traffic prevents power down of this part of the hardware path.

2. The GPU transmits pixel data to the display through the main link of the DisplayPort interface. This prevents power down of source transmitter (TX) and receiver (RX)

It is unclear how much power savings FreeSync Panel Replay can achieve compared to PSR. Before seeing these patches, we hadn’t heard AMD mention this feature, nor found any relevant results in search engines.

This patch series has about a thousand lines of new code. However, due to the timing of these patches being submitted, they are not expected to be merged into the mainline until at least the v6.6 kernel cycle later this year.

Patch address: https://lists.freedesktop.org/archives/amd-gfx/2023-June/094605.html

In addition to announcing this new feature, AMD has released the latest version of Radeon™ Software for Linux.

The software supports Ubuntu 20.04, RHEL 8.2 and other operating systems, and provides two driver options, AMDGPU All-Open and AMDGPU-Pro.