From ba162ae749a5526025a6f1061bfcbb301a6adb65 Mon Sep 17 00:00:00 2001 From: Rodrigo Siqueira Date: Mon, 22 Jan 2024 14:25:01 -0700 Subject: Documentation/gpu: Introduce a simple contribution list for display code MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This commit adds a contribution list for display under the kernel documentation with some first suggestions. It also drops an old TODO list from the display folder. Cc: Mario Limonciello Cc: Alex Deucher Cc: Harry Wentland Cc: Hamza Mahfooz Cc: Christian König Cc: Aurabindo Pillai Reviewed-by: Mario Limonciello Acked-by: Christian König Acked-by: Hamza Mahfooz Signed-off-by: Rodrigo Siqueira Signed-off-by: Alex Deucher --- .../gpu/amdgpu/display/display-contributing.rst | 168 +++++++++++++++++++++ Documentation/gpu/amdgpu/display/index.rst | 1 + 2 files changed, 169 insertions(+) create mode 100644 Documentation/gpu/amdgpu/display/display-contributing.rst (limited to 'Documentation/gpu/amdgpu') diff --git a/Documentation/gpu/amdgpu/display/display-contributing.rst b/Documentation/gpu/amdgpu/display/display-contributing.rst new file mode 100644 index 000000000000..fdb2bea01d53 --- /dev/null +++ b/Documentation/gpu/amdgpu/display/display-contributing.rst @@ -0,0 +1,168 @@ +.. _display_todos: + +============================== +AMDGPU - Display Contributions +============================== + +First of all, if you are here, you probably want to give some technical +contribution to the display code, and for that, we say thank you :) + +This page summarizes some of the issues you can help with; keep in mind that +this is a static page, and it is always a good idea to try to reach developers +in the amdgfx or some of the maintainers. Finally, this page follows the DRM +way of creating a TODO list; for more information, check +'Documentation/gpu/todo.rst'. + +Gitlab issues +============= + +Users can report issues associated with AMD GPUs at: + +- https://gitlab.freedesktop.org/drm/amd + +Usually, we try to add a proper label to all new tickets to make it easy to +filter issues. If you can reproduce any problem, you could help by adding more +information or fixing the issue. + +Level: diverse + +IGT +=== + +`IGT`_ provides many integration tests that can be run on your GPU. We always +want to pass a large set of tests to increase the test coverage in our CI. If +you wish to contribute to the display code but are unsure where a good place +is, we recommend you run all IGT tests and try to fix any failure you see in +your hardware. Keep in mind that this failure can be an IGT problem or a kernel +issue; it is necessary to analyze case-by-case. + +Level: diverse + +.. _IGT: https://gitlab.freedesktop.org/drm/igt-gpu-tools + +Compilation +=========== + +Fix compilation warnings +------------------------ + +Enable the W1 or W2 warning level in the kernel compilation and try to fix the +issues on the display side. + +Level: Starter + +Fix compilation issues when using um architecture +------------------------------------------------- + +Linux has a User-mode Linux (UML) feature, and the kernel can be compiled to +the **um** architecture. Compiling for **um** can bring multiple advantages +from the test perspective. We currently have some compilation issues in this +area that we need to fix. + +Level: Intermediate + +Code Refactor +============= + +Add prefix to DC functions to improve the debug with ftrace +----------------------------------------------------------- + +The Ftrace debug feature (check 'Documentation/trace/ftrace.rst') is a +fantastic way to check the code path when developers try to make sense of a +bug. Ftrace provides a filter mechanism that can be useful when the developer +has some hunch of which part of the code can cause the issue; for this reason, +if a set of functions has a proper prefix, it becomes easy to create a good +filter. Additionally, prefixes can improve stack trace readability. + +The DC code does not follow some prefix rules, which makes the Ftrace filter +more complicated and reduces the readability of the stack trace. If you want +something simple to start contributing to the display, you can make patches for +adding prefixes to DC functions. To create those prefixes, use part of the file +name as a prefix for all functions in the target file. Check the +'amdgpu_dm_crtc.c` and `amdgpu_dm_plane.c` for some references. However, we +strongly advise not to send huge patches changing these prefixes; otherwise, it +will be hard to review and test, which can generate second thoughts from +maintainers. Try small steps; in case of double, you can ask before you put in +effort. We recommend first looking at folders like dceXYZ, dcnXYZ, basics, +bios, core, clk_mgr, hwss, resource, and irq. + +Level: Starter + +Reduce code duplication +----------------------- + +AMD has an extensive portfolio with various dGPUs and APUs that amdgpu +supports. To maintain the new hardware release cadence, DCE/DCN was designed in +a modular design, making the bring-up for new hardware fast. Over the years, +amdgpu accumulated some technical debt in the code duplication area. For this +task, it would be a good idea to find a tool that can discover code duplication +(including patterns) and use it as guidance to reduce duplications. + +Level: Intermediate + +Make atomic_commit_[check|tail] more readable +--------------------------------------------- + +The functions responsible for atomic commit and tail are intricate and +extensive. In particular `amdgpu_dm_atomic_commit_tail` is a long function and +could benefit from being split into smaller helpers. Improvements in this area +are more than welcome, but keep in mind that changes in this area will affect +all ASICs, meaning that refactoring requires a comprehensive verification; in +other words, this effort can take some time for validation. + +Level: Advanced + +Documentation +============= + +Expand kernel-doc +----------------- + +Many DC functions do not have a proper kernel-doc; understanding a function and +adding documentation is a great way to learn more about the amdgpu driver and +also leave an outstanding contribution to the entire community. + +Level: Starter + +Beyond AMDGPU +============= + +AMDGPU provides features that are not yet enabled in the userspace. This +section highlights some of the coolest display features, which could be enabled +with the userspace developer helper. + +Enable underlay +--------------- + +AMD display has this feature called underlay (which you can read more about at +'Documentation/GPU/amdgpu/display/mpo-overview.rst') which is intended to +save power when playing a video. The basic idea is to put a video in the +underlay plane at the bottom and the desktop in the plane above it with a hole +in the video area. This feature is enabled in ChromeOS, and from our data +measurement, it can save power. + +Level: Unknown + +Adaptive Backlight Modulation (ABM) +----------------------------------- + +ABM is a feature that adjusts the display panel's backlight level and pixel +values depending on the displayed image. This power-saving feature can be very +useful when the system starts to run off battery; since this will impact the +display output fidelity, it would be good if this option was something that +users could turn on or off. + +Level: Unknown + + +HDR & Color management & VRR +---------------------------- + +HDR, Color Management, and VRR are huge topics and it's hard to put these into +concise ToDos. If you are interested in this topic, we recommend checking some +blog posts from the community developers to better understand some of the +specific challenges and people working on the subject. If anyone wants to work +on some particular part, we can try to help with some basic guidance. Finally, +keep in mind that we already have some kernel-doc in place for those areas. + +Level: Unknown diff --git a/Documentation/gpu/amdgpu/display/index.rst b/Documentation/gpu/amdgpu/display/index.rst index aa89e8f9ab89..f0c342e00a39 100644 --- a/Documentation/gpu/amdgpu/display/index.rst +++ b/Documentation/gpu/amdgpu/display/index.rst @@ -92,4 +92,5 @@ table of content: dcn-blocks.rst mpo-overview.rst dc-debug.rst + display-contributing.rst dc-glossary.rst -- cgit v1.2.3