Nvidia Tegra 2 (tegra20)

Bootloader
Currently, instead of the standard proprietary Aboot (using fastboot service), there is open-source u-boot development in progress for some Tegra devices. You can check it out in this repository

Components (source)

 * Mesa-3D (minimal implementation, not complete enough (GL 1.4) to run XWayland (requires GL 2.1 or GLES2)
 * xf86-video-tegra (2D acceleration for X11, EXA)
 * libvdpau-tegra

Usability
Wayland:
 * Phosh works, but UI is accelerated trough llvmpipe (software rendering), thus is slow.
 * Plasma mobile not tested (please update)

X11:
 * Xfce4 and Mate desktop will run on 2D acceleration.
 * Hildon requires an OpenGL backend.
 * As of cogl 1.22.2 the clutter/cogl backend requires stencil buffers . This not yet implemented in the grate-driver.

Video Decoding
Video Decoder Engine (VDE) was added to mainline kernel v4.16. The grate-driver includes hardware h264 decoding with libvdpau-tegra.

The vdpau driver does not support h264 videos encoded with:
 * weighted prediction
 * CABAC

Sample video that can be decoded with hardware acceleration: https://peach.blender.org/trailer-page/

Mesa3D Gallium driver
https://github.com/grate-driver/mesa


 * Host1x ABI rework (required before mesa implemenetation): (G. docs)
 * migrate from TGSI to NIR
 * establishing demos that work, where can be seen regression

New Device Trees
To generate the correct RAM timings for new Tegra 3 devices from known kernel sources, you can start from the known (downstream) RAM model code, and generate valid timings using this tool by Ion Agorria: https://gitlab.com/IonAgorria/tegra-timings-generator.

The #postmarketOS-on-transformers:matrix.org chat room will also be an excellent starting point for the porting of any new Tegra 2/3/4 device, also outside strictly the ASUS Transformer series