AMD or ATI

AMD GPU support requires the linux-firmware-amd package. If you have installed the linux or linux-lts packages, it will be installed as a dependency. If you installed a version-specific kernel package (e.g., linux5.4), it may be necessary to manually install linux-firmware-amd.

OpenGL

Install the Mesa DRI package, mesa-dri. This is already included in the xorg meta-package, but it is needed when installing Xorg via xorg-minimal or for running a Wayland compositor.

Vulkan

Install vulkan-loader, the Khronos Vulkan Loader. Then install one or both of the Mesa AMD Vulkan driver, mesa-vulkan-radeon; or the GPUOpen AMD Vulkan driver, amdvlk.

Xorg

Installing the xorg meta-package will pull in both xf86-video-amdgpu and, for older hardware, xf86-video-ati. If you install xorg-minimal, choose one of these Xorg driver packages to match your hardware. The amdgpu driver should support cards built on AMD's "Graphics Core Next 1.2" architecture, introduced circa 2012.

Video acceleration

Install the mesa-vaapi and mesa-vdpau packages.