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 this
8reason, our Display Core Driver is divided into two pieces:
9
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.
15
16------------------
17DC Code validation
18------------------
19
20Maintaining the same code base across multiple OSes requires a lot of
21synchronization effort between repositories and exhaustive validation. In the
22DC case, we maintain a tree to centralize code from different parts. The shared
23repository has integration tests with our Internal Linux CI farm, and we run a
24comprehensive set of IGT tests in various AMD GPUs/APUs (mostly recent dGPUs
25and APUs). Our CI also checks ARM64/32, PPC64/32, and x86_64/32 compilation
26with DCN enabled and disabled.
27
28When we upstream a new feature or some patches, we pack them in a patchset with
29the 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
31those patches are under a DC version tested as follows:
32
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
39  patch is dropped.
40* Finally, developers wait a few days for community feedback before we merge
41  the series.
42
43It is good to stress that the test phase is something that we take extremely
44seriously, and we never merge anything that fails our validation. Follows an
45overview of our test set:
46
47#. Manual test
48    * 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 test
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.
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 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.
69
70Notice that someone from our test team will always reply to the cover letter
71with the test report.
72
73--------------
74DC Information
75--------------
76
77The display pipe is responsible for "scanning out" a rendered frame from the
78GPU 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 below
86table of content:
87
88.. toctree::
89
90   display-manager.rst
91   dcn-overview.rst
92   dcn-blocks.rst
93   mpo-overview.rst
94   dc-debug.rst
95   display-contributing.rst
96   dc-glossary.rst
97