1 .. _amdgpu-display-core:
3 ===================================
4 drm/amd/display - Display Core (DC)
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7 AMD display engine is partially shared with other operating systems; for this
8 reason, our Display Core Driver is divided into two pieces:
10 #. **Display Core (DC)** contains the OS-agnostic components. Things like
11 hardware programming and resource management are handled here.
12 #. **Display Manager (DM)** contains the OS-dependent components. Hooks to the
13 amdgpu base driver and DRM are implemented here. For example, you can check
14 display/amdgpu_dm/ folder.
20 Maintaining the same code base across multiple OSes requires a lot of
21 synchronization effort between repositories and exhaustive validation. In the
22 DC case, we maintain a tree to centralize code from different parts. The shared
23 repository has integration tests with our Internal Linux CI farm, and we run a
24 comprehensive set of IGT tests in various AMD GPUs/APUs (mostly recent dGPUs
25 and APUs). Our CI also checks ARM64/32, PPC64/32, and x86_64/32 compilation
26 with DCN enabled and disabled.
28 When we upstream a new feature or some patches, we pack them in a patchset with
29 the prefix **DC Patches for <DATE>**, which is created based on the latest
30 `amd-staging-drm-next <https://gitlab.freedesktop.org/agd5f/linux>`_. All of
31 those patches are under a DC version tested as follows:
33 * Ensure that every patch compiles and the entire series pass our set of IGT
34 test in different hardware.
35 * Prepare a branch with those patches for our validation team. If there is an
36 error, a developer will debug as fast as possible; usually, a simple bisect
37 in the series is enough to point to a bad change, and two possible actions
38 emerge: fix the issue or drop the patch. If it is not an easy fix, the bad
40 * Finally, developers wait a few days for community feedback before we merge
43 It is good to stress that the test phase is something that we take extremely
44 seriously, and we never merge anything that fails our validation. Follows an
45 overview of our test set:
48 * Multiple Hotplugs with DP and HDMI.
49 * Stress test with multiple display configuration changes via the user interface.
50 * Validate VRR behaviour.
52 * Validate MPO when playing video.
53 * Test more than two displays connected at the same time.
54 * Check suspend/resume.
58 * 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.
62 In terms of test setup for CI and manual tests, we usually use:
64 #. The latest Ubuntu LTS.
65 #. In terms of userspace, we only use fully updated open-source components
66 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.
70 Notice that someone from our test team will always reply to the cover letter
77 The display pipe is responsible for "scanning out" a rendered frame from the
78 GPU memory (also called VRAM, FrameBuffer, etc.) to a display. In other words,
81 #. Read frame information from memory;
82 #. Perform required transformation;
83 #. Send pixel data to sink devices.
85 If you want to learn more about our driver details, take a look at the below
95 display-contributing.rst