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<section id="drm-amd-display-display-core-dc">
<span id="amdgpu-display-core"></span><h1>drm/amd/display - Display Core (DC)<a class="headerlink" href="#drm-amd-display-display-core-dc" title="Link to this heading">¶</a></h1>
<p>AMD display engine is partially shared with other operating systems; for this
reason, our Display Core Driver is divided into two pieces:</p>
<ol class="arabic simple">
<li><p><strong>Display Core (DC)</strong> contains the OS-agnostic components. Things like
hardware programming and resource management are handled here.</p></li>
<li><p><strong>Display Manager (DM)</strong> contains the OS-dependent components. Hooks to the
amdgpu base driver and DRM are implemented here. For example, you can check
display/amdgpu_dm/ folder.</p></li>
</ol>
<section id="dc-code-validation">
<h2>DC Code validation<a class="headerlink" href="#dc-code-validation" title="Link to this heading">¶</a></h2>
<p>Maintaining the same code base across multiple OSes requires a lot of
synchronization effort between repositories and exhaustive validation. In the
DC case, we maintain a tree to centralize code from different parts. The shared
repository has integration tests with our Internal Linux CI farm, and we run a
comprehensive set of IGT tests in various AMD GPUs/APUs (mostly recent dGPUs
and APUs). Our CI also checks ARM64/32, PPC64/32, and x86_64/32 compilation
with DCN enabled and disabled.</p>
<p>When we upstream a new feature or some patches, we pack them in a patchset with
the prefix <strong>DC Patches for <DATE></strong>, which is created based on the latest
<a class="reference external" href="https://gitlab.freedesktop.org/agd5f/linux">amd-staging-drm-next</a>. All of
those patches are under a DC version tested as follows:</p>
<ul class="simple">
<li><p>Ensure that every patch compiles and the entire series pass our set of IGT
test in different hardware.</p></li>
<li><p>Prepare a branch with those patches for our validation team. If there is an
error, a developer will debug as fast as possible; usually, a simple bisect
in the series is enough to point to a bad change, and two possible actions
emerge: fix the issue or drop the patch. If it is not an easy fix, the bad
patch is dropped.</p></li>
<li><p>Finally, developers wait a few days for community feedback before we merge
the series.</p></li>
</ul>
<p>It is good to stress that the test phase is something that we take extremely
seriously, and we never merge anything that fails our validation. Follows an
overview of our test set:</p>
<ol class="arabic simple">
<li><dl class="simple">
<dt>Manual test</dt><dd><ul class="simple">
<li><p>Multiple Hotplugs with DP and HDMI.</p></li>
<li><p>Stress test with multiple display configuration changes via the user interface.</p></li>
<li><p>Validate VRR behaviour.</p></li>
<li><p>Check PSR.</p></li>
<li><p>Validate MPO when playing video.</p></li>
<li><p>Test more than two displays connected at the same time.</p></li>
<li><p>Check suspend/resume.</p></li>
<li><p>Validate FPO.</p></li>
<li><p>Check MST.</p></li>
</ul>
</dd>
</dl>
</li>
<li><dl class="simple">
<dt>Automated test</dt><dd><ul class="simple">
<li><p>IGT tests in a farm with GPUs and APUs that support DCN and DCE.</p></li>
<li><p>Compilation validation with the latest GCC and Clang from LTS distro.</p></li>
<li><p>Cross-compilation for PowerPC 64/32, ARM 64/32, and x86 32.</p></li>
</ul>
</dd>
</dl>
</li>
</ol>
<p>In terms of test setup for CI and manual tests, we usually use:</p>
<ol class="arabic simple">
<li><p>The latest Ubuntu LTS.</p></li>
<li><p>In terms of userspace, we only use fully updated open-source components
provided by the distribution official package manager.</p></li>
<li><p>Regarding IGT, we use the latest code from the upstream.</p></li>
<li><p>Most of the manual tests are conducted in the GNome but we also use KDE.</p></li>
</ol>
<p>Notice that someone from our test team will always reply to the cover letter
with the test report.</p>
</section>
<section id="dc-information">
<h2>DC Information<a class="headerlink" href="#dc-information" title="Link to this heading">¶</a></h2>
<p>The display pipe is responsible for “scanning out” a rendered frame from the
GPU memory (also called VRAM, FrameBuffer, etc.) to a display. In other words,
it would:</p>
<ol class="arabic simple">
<li><p>Read frame information from memory;</p></li>
<li><p>Perform required transformation;</p></li>
<li><p>Send pixel data to sink devices.</p></li>
</ol>
<p>If you want to learn more about our driver details, take a look at the below
table of content:</p>
<div class="toctree-wrapper compound">
<ul>
<li class="toctree-l1"><a class="reference internal" href="display-manager.html">AMDgpu Display Manager</a><ul>
<li class="toctree-l2"><a class="reference internal" href="display-manager.html#lifecycle">Lifecycle</a></li>
<li class="toctree-l2"><a class="reference internal" href="display-manager.html#interrupts">Interrupts</a></li>
<li class="toctree-l2"><a class="reference internal" href="display-manager.html#atomic-implementation">Atomic Implementation</a></li>
<li class="toctree-l2"><a class="reference internal" href="display-manager.html#color-management-properties">Color Management Properties</a><ul>
<li class="toctree-l3"><a class="reference internal" href="display-manager.html#dc-color-capabilities-between-dcn-generations">DC Color Capabilities between DCN generations</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="display-manager.html#blend-mode-properties">Blend Mode Properties</a><ul>
<li class="toctree-l3"><a class="reference internal" href="display-manager.html#blend-configuration-flow">Blend configuration flow</a></li>
</ul>
</li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="dcn-overview.html">Display Core Next (DCN)</a><ul>
<li class="toctree-l2"><a class="reference internal" href="dcn-overview.html#front-end-and-back-end">Front End and Back End</a></li>
<li class="toctree-l2"><a class="reference internal" href="dcn-overview.html#data-flow">Data Flow</a></li>
<li class="toctree-l2"><a class="reference internal" href="dcn-overview.html#amd-hardware-pipeline">AMD Hardware Pipeline</a></li>
<li class="toctree-l2"><a class="reference internal" href="dcn-overview.html#global-sync">Global Sync</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="dcn-blocks.html">DCN Blocks</a><ul>
<li class="toctree-l2"><a class="reference internal" href="dcn-blocks.html#dchubbub">DCHUBBUB</a></li>
<li class="toctree-l2"><a class="reference internal" href="dcn-blocks.html#hubp">HUBP</a></li>
<li class="toctree-l2"><a class="reference internal" href="dcn-blocks.html#dpp">DPP</a></li>
<li class="toctree-l2"><a class="reference internal" href="dcn-blocks.html#mpc">MPC</a></li>
<li class="toctree-l2"><a class="reference internal" href="dcn-blocks.html#opp">OPP</a></li>
<li class="toctree-l2"><a class="reference internal" href="dcn-blocks.html#dio">DIO</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="programming-model-dcn.html">DC Programming Model</a><ul>
<li class="toctree-l2"><a class="reference internal" href="programming-model-dcn.html#overview">Overview</a></li>
<li class="toctree-l2"><a class="reference internal" href="programming-model-dcn.html#display-driver-architecture-overview">Display Driver Architecture Overview</a><ul>
<li class="toctree-l3"><a class="reference internal" href="programming-model-dcn.html#basic-objects">Basic Objects</a></li>
<li class="toctree-l3"><a class="reference internal" href="programming-model-dcn.html#basic-operations">Basic Operations</a></li>
</ul>
</li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="mpo-overview.html">Multiplane Overlay (MPO)</a><ul>
<li class="toctree-l2"><a class="reference internal" href="mpo-overview.html#plane-restrictions">Plane Restrictions</a></li>
<li class="toctree-l2"><a class="reference internal" href="mpo-overview.html#cursor-restrictions">Cursor Restrictions</a></li>
<li class="toctree-l2"><a class="reference internal" href="mpo-overview.html#use-cases">Use Cases</a><ul>
<li class="toctree-l3"><a class="reference internal" href="mpo-overview.html#picture-in-picture-pip-playback-underlay-strategy">Picture-in-Picture (PIP) playback - Underlay strategy</a></li>
<li class="toctree-l3"><a class="reference internal" href="mpo-overview.html#multiple-display-mpo">Multiple Display MPO</a><ul>
<li class="toctree-l4"><a class="reference internal" href="mpo-overview.html#limitations">Limitations</a></li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="dc-debug.html">Display Core Debug tools</a><ul>
<li class="toctree-l2"><a class="reference internal" href="dc-debug.html#narrow-down-display-issues">Narrow down display issues</a><ul>
<li class="toctree-l3"><a class="reference internal" href="dc-debug.html#dc-dmesg-important-messages">DC dmesg important messages</a></li>
<li class="toctree-l3"><a class="reference internal" href="dc-debug.html#avoid-loading-display-core">Avoid loading display core</a></li>
<li class="toctree-l3"><a class="reference internal" href="dc-debug.html#display-flickering">Display flickering</a></li>
<li class="toctree-l3"><a class="reference internal" href="dc-debug.html#display-artifacts">Display artifacts</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="dc-debug.html#disabling-enabling-specific-features">Disabling/Enabling specific features</a></li>
<li class="toctree-l2"><a class="reference internal" href="dc-debug.html#dc-visual-confirmation">DC Visual Confirmation</a><ul>
<li class="toctree-l3"><a class="reference internal" href="dc-debug.html#multiple-planes-debug">Multiple Planes Debug</a></li>
<li class="toctree-l3"><a class="reference internal" href="dc-debug.html#pipe-split-debug">Pipe Split Debug</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="dc-debug.html#dtn-debug">DTN Debug</a></li>
<li class="toctree-l2"><a class="reference internal" href="dc-debug.html#collect-firmware-information">Collect Firmware information</a></li>
<li class="toctree-l2"><a class="reference internal" href="dc-debug.html#dmub-firmware-debug">DMUB Firmware Debug</a><ul>
<li class="toctree-l3"><a class="reference internal" href="dc-debug.html#trace-groups">Trace Groups</a></li>
</ul>
</li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="display-contributing.html">AMDGPU - Display Contributions</a><ul>
<li class="toctree-l2"><a class="reference internal" href="display-contributing.html#gitlab-issues">Gitlab issues</a></li>
<li class="toctree-l2"><a class="reference internal" href="display-contributing.html#igt">IGT</a></li>
<li class="toctree-l2"><a class="reference internal" href="display-contributing.html#compilation">Compilation</a><ul>
<li class="toctree-l3"><a class="reference internal" href="display-contributing.html#fix-compilation-warnings">Fix compilation warnings</a></li>
<li class="toctree-l3"><a class="reference internal" href="display-contributing.html#fix-compilation-issues-when-using-um-architecture">Fix compilation issues when using um architecture</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="display-contributing.html#code-refactor">Code Refactor</a><ul>
<li class="toctree-l3"><a class="reference internal" href="display-contributing.html#add-prefix-to-dc-functions-to-improve-the-debug-with-ftrace">Add prefix to DC functions to improve the debug with ftrace</a></li>
<li class="toctree-l3"><a class="reference internal" href="display-contributing.html#reduce-code-duplication">Reduce code duplication</a></li>
<li class="toctree-l3"><a class="reference internal" href="display-contributing.html#make-atomic-commit-check-tail-more-readable">Make atomic_commit_[check|tail] more readable</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="display-contributing.html#documentation">Documentation</a><ul>
<li class="toctree-l3"><a class="reference internal" href="display-contributing.html#expand-kernel-doc">Expand kernel-doc</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="display-contributing.html#beyond-amdgpu">Beyond AMDGPU</a><ul>
<li class="toctree-l3"><a class="reference internal" href="display-contributing.html#enable-underlay">Enable underlay</a></li>
<li class="toctree-l3"><a class="reference internal" href="display-contributing.html#adaptive-backlight-modulation-abm">Adaptive Backlight Modulation (ABM)</a></li>
<li class="toctree-l3"><a class="reference internal" href="display-contributing.html#hdr-color-management-vrr">HDR & Color management & VRR</a></li>
</ul>
</li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="dc-glossary.html">DC Glossary</a></li>
</ul>
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