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diff --git a/Documentation/gpu/introduction.rst b/Documentation/gpu/introduction.rst index fccbe375244d..3cd0c8860b94 100644 --- a/Documentation/gpu/introduction.rst +++ b/Documentation/gpu/introduction.rst @@ -51,6 +51,22 @@ and "FIXME" where the interface could be cleaned up. Also read the :ref:`guidelines for the kernel documentation at large <doc_guide>`. +Documentation Requirements for kAPI +----------------------------------- + +All kernel APIs exported to other modules must be documented, including their +datastructures and at least a short introductory section explaining the overall +concepts. Documentation should be put into the code itself as kerneldoc comments +as much as reasonable. + +Do not blindly document everything, but document only what's relevant for driver +authors: Internal functions of drm.ko and definitely static functions should not +have formal kerneldoc comments. Use normal C comments if you feel like a comment +is warranted. You may use kerneldoc syntax in the comment, but it shall not +start with a /** kerneldoc marker. Similar for data structures, annotate +anything entirely private with ``/* private: */`` comments as per the +documentation guide. + Getting Started =============== @@ -96,3 +112,65 @@ Please conduct yourself in a respectful and civilised manner when interacting with community members on mailing lists, IRC, or bug trackers. The community represents the project as a whole, and abusive or bullying behaviour is not tolerated by the project. + +Simple DRM drivers to use as examples +===================================== + +The DRM subsystem contains a lot of helper functions to ease writing drivers for +simple graphic devices. For example, the `drivers/gpu/drm/tiny/` directory has a +set of drivers that are simple enough to be implemented in a single source file. + +These drivers make use of the `struct drm_simple_display_pipe_funcs`, that hides +any complexity of the DRM subsystem and just requires drivers to implement a few +functions needed to operate the device. This could be used for devices that just +need a display pipeline with one full-screen scanout buffer feeding one output. + +The tiny DRM drivers are good examples to understand how DRM drivers should look +like. Since are just a few hundreds lines of code, they are quite easy to read. + +External References +=================== + +Delving into a Linux kernel subsystem for the first time can be an overwhelming +experience, one needs to get familiar with all the concepts and learn about the +subsystem's internals, among other details. + +To shallow the learning curve, this section contains a list of presentations +and documents that can be used to learn about DRM/KMS and graphics in general. + +There are different reasons why someone might want to get into DRM: porting an +existing fbdev driver, write a DRM driver for a new hardware, fixing bugs that +could face when working on the graphics user-space stack, etc. For this reason, +the learning material covers many aspects of the Linux graphics stack. From an +overview of the kernel and user-space stacks to very specific topics. + +The list is sorted in reverse chronological order, to keep the most up-to-date +material at the top. But all of them contain useful information, and it can be +valuable to go through older material to understand the rationale and context +in which the changes to the DRM subsystem were made. + +Conference talks +---------------- + +* `An Overview of the Linux and Userspace Graphics Stack <https://www.youtube.com/watch?v=wjAJmqwg47k>`_ - Paul Kocialkowski (2020) +* `Getting pixels on screen on Linux: introduction to Kernel Mode Setting <https://www.youtube.com/watch?v=haes4_Xnc5Q>`_ - Simon Ser (2020) +* `Everything Great about Upstream Graphics <https://www.youtube.com/watch?v=kVzHOgt6WGE>`_ - Simona Vetter (2019) +* `An introduction to the Linux DRM subsystem <https://www.youtube.com/watch?v=LbDOCJcDRoo>`_ - Maxime Ripard (2017) +* `Embrace the Atomic (Display) Age <https://www.youtube.com/watch?v=LjiB_JeDn2M>`_ - Simona Vetter (2016) +* `Anatomy of an Atomic KMS Driver <https://www.youtube.com/watch?v=lihqR9sENpc>`_ - Laurent Pinchart (2015) +* `Atomic Modesetting for Drivers <https://www.youtube.com/watch?v=kl9suFgbTc8>`_ - Simona Vetter (2015) +* `Anatomy of an Embedded KMS Driver <https://www.youtube.com/watch?v=Ja8fM7rTae4>`_ - Laurent Pinchart (2013) + +Slides and articles +------------------- + +* `The Linux graphics stack in a nutshell, part 1 <https://lwn.net/Articles/955376/>`_ - Thomas Zimmermann (2023) +* `The Linux graphics stack in a nutshell, part 2 <https://lwn.net/Articles/955708/>`_ - Thomas Zimmermann (2023) +* `Understanding the Linux Graphics Stack <https://bootlin.com/doc/training/graphics/graphics-slides.pdf>`_ - Bootlin (2022) +* `DRM KMS overview <https://wiki.st.com/stm32mpu/wiki/DRM_KMS_overview>`_ - STMicroelectronics (2021) +* `Linux graphic stack <https://studiopixl.com/2017-05-13/linux-graphic-stack-an-overview>`_ - Nathan Gauër (2017) +* `Atomic mode setting design overview, part 1 <https://lwn.net/Articles/653071/>`_ - Simona Vetter (2015) +* `Atomic mode setting design overview, part 2 <https://lwn.net/Articles/653466/>`_ - Simona Vetter (2015) +* `The DRM/KMS subsystem from a newbie’s point of view <https://bootlin.com/pub/conferences/2014/elce/brezillon-drm-kms/brezillon-drm-kms.pdf>`_ - Boris Brezillon (2014) +* `A brief introduction to the Linux graphics stack <https://blogs.igalia.com/itoral/2014/07/29/a-brief-introduction-to-the-linux-graphics-stack/>`_ - Iago Toral (2014) +* `The Linux Graphics Stack <https://blog.mecheye.net/2012/06/the-linux-graphics-stack/>`_ - Jasper St. Pierre (2012) |