Intel's Linux DRM Driver To Enable PSR2 Power-Savings By Default
Written by Michael Larabel in Intel on 14 February 2019 at 06:00 PM EST. 6 Comments
INTEL --
The Intel DRM/KMS kernel driver will soon see PSR2 panel self refresh capabilities enabled by default for allowing more power-savings on Intel-powered ultrabooks/notebooks.

For a while now Intel's Direct Rendering Manager driver has enabled Panel Self Refresh (PSR) by default as well as other power-savings features like frame-buffer compression (FBC). But the newer Panel Self Refresh standard, PSR2, for eDP displays has not been enabled by default.

Under select hardware/driver combinations there previously was some display corruption issues as well as insufficient testing on enough hardware to enable PSR2 by default, but now that has improved and the Intel open-source developers appear ready to enable it by default.

Intel's José Roberto de Souza sent out a patch series that concludes with enabling PSR2 by default. "The support for PSR2 was polished, IGT tests for PSR2 was added and it was tested performing regular user workloads like browsing, editing documents and compiling Linux, so it is time to enable it by default and enjoy even more power-savings."

One of the main power-savings improvements with the PSR2 standard is the ability to do partial frame updates. For cases like the system time updating on a toolbar or a cursor flashing, PSR2 allows for updating only that portion of the screen and not the entire display. This allows for keeping the hardware in a low-power state longer due to only having to update only a select portion of the display.

I'll work on getting some PSR2 Intel Linux power consumption tests out shortly. Given the timing of this patch though, it's a bit late that we might not see it land with the upcoming Linux 5.1 kernel but could be delayed until Linux 5.2.
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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 10,000 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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