Detailed information on Mali GPUs, and instructions on installing the proprietary drivers, can be found on the MaliGraphics page. This page is dedicated to documenting the new open-source Panfrost and Lima drivers introduced in Debian 11.
The free and open-source Panfrost and Lima drivers for Mali GPUs are part of Mesa and are fully free software. Compared to the proprietary drivers, they have much better stability and software compatibility and are recommended for the average user.
The Lima driver provides support for the older "Utgard" Mali GPUs, while Panfrost provides support for the newer Midgard and Bifrost GPUs. Valhall support is pending.
Debian 11 comes with Mesa 20.3 which supports the Mali 400 and 450 GPUs via the Lima driver, and various Mali G-series and T-series GPUs via the Panfrost driver. This will cover most modern ARM SoCs, including those found in the Pinebook and Pinebook Pro devices. Mali Gxx devices (also known as "Bifrost" chips) are supported experimentally and require an extra environment variable to be set before they'll use the Panfrost driver, as documented in the Configuration section below.
In terms of specifically supported GPUs, Panfrost mainly supports the Mali T720 (only up to OpenGL 2.1 and OpenGL ES 2.0), Mali T760, Mali T820, Mali T860, Mali G72, Mali G31, and Mali G52.
Other Midgard and Bifrost chips (T604, T620, T830, T880, G71, G51, G76) may work but may be buggy.
Most of the hardware in question theoretically supports OpenGL ES 3.0, Vulkan 1.1, and OpenGL 4.6. In the version of Mesa that comes with Debian 11 (Mesa 20.3), Panfrost supports OpenGL 2.1 and OpenGL ES 3.0 (2.0 on Bifrost) without any further tweaks necessary. If additional features are required, OpenGL 3.1 and OpenGL ES 3.1 are available with newer versions of Mesa. See the Panfrost documentation for how to build.
The Panfrost driver stack implementations of OpenGL and OpenGL ES are non-conformant, as per the official documentation.
Which driver should I use?
Between the Panfrost/Lima driver and the non-free drivers also packaged and in Debian/non-free, the Panfrost/Lima driver is almost always recommended. However, incomplete support for OpenGL and nonexistent support for Vulkan may be a concern for some use-cases. Some workloads may also see better performance with the non-free driver, though successive Mesa versions are closing this gap and even demonstrating better performance than the non-free driver in Panfrost/Lima with many workloads.
Experimentation is recommended if you're in a performance or compatibility-critical environment, however average desktop users should stick with the Panfrost/Lima drivers to see the best stability.
OpenCL support is not implemented yet. Hardware video acceleration is not within the scope of the Panfrost or Lima drivers.
The Lima project page - https://gitlab.freedesktop.org/lima/
The Panfrost project page - https://panfrost.freedesktop.org/
The Panfrost documentation - https://gitlab.freedesktop.org/mesa/mesa/-/blob/master/docs/drivers/panfrost.rst