Page History

...

      Userland uses dispmanx for rendering graphics and video. With vc4graphics instead of dispmanx, DRM (Direct Rendering Manager) module is used.  DRM is a subsystem of the Linux kernel responsible for interfacing with GPUs of modern video cards. DRM is a kernel module that gives direct hardware access to DRI clients. Westeros-dispmanx is suppressed and westeros-drm is used for rendering.  Westeros-sink is enabled to use v4l2 by modifying soc-path to v4l2.  Westeros was updated to latest revision for supporting video codecs that are already used.

List of changes done

• https://code.rdkcentral.com/r/c/components/generic/rdk-oe/meta-cmf-raspberrypi/+/39272
• https://github.com/WebPlatformForEmbedded/meta-wpe/pull/450
• https://github.com/agherzan/meta-raspberrypi/pull/647, this pull was modified for CMF as  https://code.rdkcentral.com/r/c/rdk/components/opensource/oe/meta-raspberrypi/+/39347
• https://code.rdkcentral.com/r/c/components/generic/rdk-oe/meta-cmf-raspberrypi/+/39279

• https://code.rdkcentral.com/r/c/components/generic/rdk-oe/meta-cmf-raspberrypi/+/39287

• https://code.rdkcentral.com/r/c/components/generic/rdk-oe/meta-cmf-raspberrypi/+/39285
• https://code.rdkcentral.com/r/c/components/opensourcegeneric/rdk-oe/meta-cmf-raspberrypi/+/3934739284

 System Work Flow

           Direct Rendering Infrastructure (DRI) provide interface to interface Mesa, OpenGL and other 3D rendering API libraries with the device drivers and hardware. Mesa also contains an implementation of software rendering called swrast that allows shaders to run on the CPU as a fallback when no graphics hardware accelerators are present. The Gallium software rasterizer is known as softpipe or when built with support for LLVM llvmpipe, which generates CPU code at runtime

...

• http://heim.ifi.uio.no/~knuto/kernel/4.14/gpu/vc4.html?highlight=vc4
• https://en.wikipedia.org/wiki/Free_and_open-source_graphics_device_driver
• https://en.wikipedia.org/wiki/Mesa_(computer_graphics)
• https://www.raspberrypi.org/blog/open-source-arm-userspace/
• https://en.wikipedia.org/wiki/EGL_(API)
• https://www.khronos.org/opengl/wiki/Platform_specifics:_Linux
• https://en.wikipedia.org/wiki/OpenGL
• https://elinux.org/Raspberry_Pi_VideoCore_APIs