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1.. _amdgpu-display-core:2 3===================================4drm/amd/display - Display Core (DC)5===================================6 7AMD display engine is partially shared with other operating systems; for this8reason, our Display Core Driver is divided into two pieces:9 10#. **Display Core (DC)** contains the OS-agnostic components. Things like11 hardware programming and resource management are handled here.12#. **Display Manager (DM)** contains the OS-dependent components. Hooks to the13 amdgpu base driver and DRM are implemented here. For example, you can check14 display/amdgpu_dm/ folder.15 16------------------17DC Code validation18------------------19 20Maintaining the same code base across multiple OSes requires a lot of21synchronization effort between repositories and exhaustive validation. In the22DC case, we maintain a tree to centralize code from different parts. The shared23repository has integration tests with our Internal Linux CI farm, and we run a24comprehensive set of IGT tests in various AMD GPUs/APUs (mostly recent dGPUs25and APUs). Our CI also checks ARM64/32, PPC64/32, and x86_64/32 compilation26with DCN enabled and disabled.27 28When we upstream a new feature or some patches, we pack them in a patchset with29the prefix **DC Patches for <DATE>**, which is created based on the latest30`amd-staging-drm-next <https://gitlab.freedesktop.org/agd5f/linux>`_. All of31those patches are under a DC version tested as follows:32 33* Ensure that every patch compiles and the entire series pass our set of IGT34 test in different hardware.35* Prepare a branch with those patches for our validation team. If there is an36 error, a developer will debug as fast as possible; usually, a simple bisect37 in the series is enough to point to a bad change, and two possible actions38 emerge: fix the issue or drop the patch. If it is not an easy fix, the bad39 patch is dropped.40* Finally, developers wait a few days for community feedback before we merge41 the series.42 43It is good to stress that the test phase is something that we take extremely44seriously, and we never merge anything that fails our validation. Follows an45overview of our test set:46 47#. Manual test48 * Multiple Hotplugs with DP and HDMI.49 * Stress test with multiple display configuration changes via the user interface.50 * Validate VRR behaviour.51 * Check PSR.52 * Validate MPO when playing video.53 * Test more than two displays connected at the same time.54 * Check suspend/resume.55 * Validate FPO.56 * Check MST.57#. Automated test58 * IGT tests in a farm with GPUs and APUs that support DCN and DCE.59 * Compilation validation with the latest GCC and Clang from LTS distro.60 * Cross-compilation for PowerPC 64/32, ARM 64/32, and x86 32.61 62In terms of test setup for CI and manual tests, we usually use:63 64#. The latest Ubuntu LTS.65#. In terms of userspace, we only use fully updated open-source components66 provided by the distribution official package manager.67#. Regarding IGT, we use the latest code from the upstream.68#. Most of the manual tests are conducted in the GNome but we also use KDE.69 70Notice that someone from our test team will always reply to the cover letter71with the test report.72 73--------------74DC Information75--------------76 77The display pipe is responsible for "scanning out" a rendered frame from the78GPU memory (also called VRAM, FrameBuffer, etc.) to a display. In other words,79it would:80 81#. Read frame information from memory;82#. Perform required transformation;83#. Send pixel data to sink devices.84 85If you want to learn more about our driver details, take a look at the below86table of content:87 88.. toctree::89 90 display-manager.rst91 dcn-overview.rst92 dcn-blocks.rst93 mpo-overview.rst94 dc-debug.rst95 display-contributing.rst96 dc-glossary.rst97