AMDGPU Linux 5.5 Changes Being Prepped With HDCP Support, LRU Bulk Moves Re-Enabled
Written by Michael Larabel in Radeon on 25 September 2019 at 11:36 AM EDT. 19 Comments
RADEON --
While the Linux 5.4 merge window doesn't even end until this weekend, as is usual traditional with the DRM-Next cutoff having been weeks ago, the open-source DRM driver developers are already working on their changes for what will ultimately go into Linux 5.5. On the AMD side, the AMDGPU kernel graphics driver already has some interesting work accumulating.

The AMD Linux graphics driver development repository already has a drm-next-5.5-wip branch going with their early work anticipated for the next kernel cycle. The Linux 5.5 development will officially kickoff following the Linux 5.4 release in November but not see its stable debut until 2020.

While still very early in the work towards the AMDGPU driver state for Linux 5.5, so far this work-in-progress tree has:

- Re-enabling of the LRU bulk moves functionality. This is a performance win for demanding Linux games and can help OpenCL performance and related work. It's too bad there's the wait until Linux 5.5 since the fixes for the LRU bulk moves have landed in Linux 5.0, but at least this performance optimization will be here in a few months by default.

- The recent work over the past few months on HDCP support for Raven Ridge and newer. Granted, many open-source fans won't be happy to hear about High-bandwidth Digital Content Protection (HDCP) support coming to the AMD Linux driver but it's already been supported by the open-source Intel driver and NVIDIA's proprietary driver. The HDCP support is actually good news in one respect as it's likely at the behest of Google with AMD APUs now appearing in Chromebooks, similar to Google having pushed along Intel's Linux HDCP support. This HDCP support could lead to enabling AMD to compete with other design wins for other Linux-powered devices. If you don't want AMD HDCP support, at least for now they have it exposed as a Kconfig option so you can disable building the support via DRM_AMD_DC_HDCP.

- Full RAS support is now enabled by default, in help of workstation/professional efforts.

- SRIOV is coming to at least one Navi 12 GPU (0x7362).

- Updated golden register settings for Navi 14.

- Support for updating page tables directly while in a page fault, PD/PT clears directly in the fault handler, and related changes. It's not clear from the commit messages if this should yield a real performance change.

- AMDKFD compute support for Renoir APUs.

- Various DC/display updates.

The in-development AMDGPU driver work ahead of Linux 5.5 can be tested via this code branch.
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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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