For those that may be new to the open-source graphics driver world or just haven't been paying attention to all our kernel news and reporting in recent months, here's all the full DRM/KMS graphics drivers currently part of the mainline tree and to be found in the Linux 3.13 kernel.
Exynos - The DRM driver that's been part of the kernel tree for several release cycles now and is for the Samsung Exynos ARM SoCs. The Exynos DRM driver is officially maintained by Samsung and has matured a fair amount since being mainline, but this is only the kernel bits and Samsung has no open-source 3D user-space for their ARM chips.
GMA500 - A simple Intel Poulsbo GMA500/GMA600 Atom SoC driver. This driver is very simple and developed by Alan Cox and others without the official support of Intel. The GMA500 DRM driver just provides kernel mode-setting support and doesn't have any 3D bits due to the older Atom SoCs relying upon closed-up PowerVR graphics technology.
i915 - The feature-rich Intel DRM driver that supports from the i830 series up through Haswell graphics. With Linux 3.13 there's also early support for next year's Broadwell processors.
MGA200 - The basic kernel mode-setting driver for supporting MGA G200 graphics adapters commonly found in servers. This driver was hacked together by David Airlie at Red Hat since in the RHEL/Fedora world they're trying to moving to DRM/KMS-only drivers and Matrox happens still to be in wide use among server systems. This MGA200 driver doesn't offer up any hardware acceleration and is just for use with the generic xf86-video-modesetting driver.
MSM - This is the latest ARM DRM graphics driver. MSM is the Freedreno kernel driver created by Rob Clark for Qualcomm Snapdragon/Adreno graphics hardware. Freedreno has been advancing greatly and serves as a leading example of a fully open-source ARM graphics driver.
Nouveau - The open-source reverse-engineered NVIDIA graphics driver! This driver supports nearly all of NVIDIA's graphics hardware.
OMAPDRM - The KMS driver for Texas Instruments' OMAP2, OMAP3, and OMAP4 ARM boards. Sadly this driver hasn't seen too much activity since Rob Clark left TI but seems to still work well during all of my OMAP4460 PandaBoard ES testing. This driver doesn't support 3D but just mode-setting, 2D, and video overlays support.
QXL - This is the new QXL virtual GPU DRM driver for use with SPICE virtualization. This driver is to be used with the updated X.Org QXL driver on SPICE systems. The QXL driver comes out of Red Hat where David Airlie is still working on his experimental Virgil3D project for 3D guest GPU support with KVM/QEMU guests.
Radeon - The main ATI/AMD Radeon DRM/KMS driver and the many generations of GPUs.
RCAR-DU - A DRM driver for the Renesas R-Car display unit.
SHMOBILE - The basic DRM driver for SH Mobile chipsets.
TEGRA - The in-development ARM Tegra graphics driver for their modern ARM SoCs. This started out as a community project but NVIDIA Corp has begun supporting this open-source Tegra graphics initiative. The user-space side -- including 3D support -- is still very much a work-in-progress.
TILCDC - A basic DRM driver for the Texas Instruments LCDC display controller.
UDL - The DRM driver for DisplayLink USB-based video adapters. There hasn't been too much DisplayLink Linux news recently, but in my most recent testing of the DisplayLink USB adapters / displays they've still worken out fine.
VMWGFX - The VMware virtual GPU DRM driver for the kernel bits to having 2D/3D acceleration in VMware guests when paired with their vmwgfx Gallium3D driver.
Living outside of the kernel tree is still the VIA KMS driver and a few others in the ARM space, but that's where the situation stands for Linux 3.13.