AMDGPU DC Looks To Have PSR Squared Away - Power-Savings For Newer AMD Laptops
Written by Michael Larabel in Radeon on 18 October 2019 at 04:00 AM EDT. 15 Comments
RADEON --
It looks like as soon as Linux 5.5 is where the AMDGPU kernel driver could be ready with Panel Self Refresh (PSR) support for enabling this power-savings feature on newer AMD laptops.

While Intel's Linux driver stack has been supporting Panel Self Refresh for years, the AMD support in their open-source Linux driver code has been a long time coming. We've seen them working towards the support since Raven Ridge and now it appears the groundwork has been laid and they are ready to flip it on within the Display Core "DC" code.

Panel Self Refresh is for laptops with eDP panels and designs to needlessly sending the same screen contents for updating on the display. PSR thus allows for powering down some elements of the graphics processor when the screen contents are static. At least on the Intel side, they claimed benefits of 25%+ in lower power consumption of the GPU when PSR is enabled. I haven't seen any recent AMD numbers but the efficiency improvements are likely similar.

This support though relies upon a capable eDP panel and AMD graphics with a supported DMCU (Display MicroController Unit), which at least under Linux appears to be for Raven Ridge and newer.

As part of 37 patches for DC sent out on Thursday, PSR is now enabled for supported panels. This power-savings feature thus should make it for the Linux 5.5 kernel cycle barring any last minute issues from coming up.
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Michael Larabel is the principal author of Phoronix.com 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 OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter or contacted via MichaelLarabel.com.

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