AMD Re-Enables Scatter/Gather Support For All APUs On Linux

Written by Michael Larabel in Radeon on 9 February 2023 at 03:00 PM EST. Add A Comment
AMD has made some late changes for Linux 6.2 around the Scatter/Gather (S/G) functionality for APUs that enables display scan-out from system memory.

AMD recently disabled Scatter/Gather for select APUs based on the Display Core Next (DCN) IP block version after users reported flickering with the functionality enabled. AMD disabled Scatter/Gather for DCN 2.1.0, DCN 3.1.2, DCN 3.1.3, and DCN 3.1.5 based APUs. But that turned out to open a separate can of worms: running without Scatter/Gather for the APUs can lead to frame-buffer errors and blank displays when under memory pressure or the display support outright breaking for mobile systems with a limited amount of RAM carved out for video use (like Google Chromebooks).

AMD hasn't been able to reproduce the Scatter/Gather problems reported by some users around display flickering while they also need to balance the serious side effects of a bad experience when under system memory pressure. So as a late change for Linux 6.2, they are re-enabling Scatter/Gather for the DCN hardware that previously disabled it. Meanwhile they also introduce a new AMDGPU kernel module option to disable the S/G support should you be running into issues on your hardware.

By default the AMDGPU driver will attempt to use S/G display support for capable APUs but if the amdgpu.sg_display=0 option is set it will disable the feature.

Scatter-Gather broken
Nope, that's not right... Per several bug reports in recent weeks for APUs / integrated graphics traced back to the S/G behavior.

Among those originally reporting problems with the default Scatter/Gather behavior were flickering or constant solid white screens on a Ryzen 9 7950X desktop with integrated graphics and sporadic flickering with a Ryzen 7 PRO 6850U within a ThinkPad T14 Gen 3. Within those bug reports are also further comments like affecting an older Dell G5 5505 with Ryzen 7 4800H.

So Scatter/Gather is back to being enabled while if you encounter any flickering or display issues, try the new amdgpu.sg_display=0 option to disable Scatter/Gather. These latest minute changes for Linux 6.2 were sent out today for queuing ahead of Linux 6.2-rc8 this weekend. These changes will likely be back-ported to the stable kernel series as well considering it affects users on existing stable kernel versions.
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Michael Larabel is the principal author of 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 automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via

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