The first of the AMD Radeon HD 6000 "Northern Islands" graphics cards launched late last year, and while the open-source Linux driver support is technically there for those interested in this alternative to the proprietary Catalyst driver, the support is still largely broken. Here is a quick look.
It was back in January that AMD began pushing open-source Radeon HD 6000 series support with KMS and Mesa/Gallium3D support, which covered all of the "Northern Islands" ASICs. In February, AMD then released the first part of the AMD "Cayman" documentation, which is their Radeon HD 6900 series and architecturally is different from the rest of the HD 6000 series. In March there was then Cayman KMS support and in late May there was finally Cayman accelerated support for EXA/X-Video and Mesa/Gallium3D.
Exactly one month ago, I wrote that the Northern Islands support was busted on open-source. Still, even with the most recent kernel code as of yesterday following another DRM pull with more bug-fixes, the Northern Islands and Cayman code is still not very useful for those into OpenGL gaming. The Linux 3.0 kernel development cycle is ending, but still there are problems.
When running OpenGL games and other select workloads, it is choppy as shown one month ago in the video as the GPU keeps being tapped in the wrong way. If looking at the dmesg kernel output, there is a continuous stream of IB scheduling problems. This is a slightly different issue (though perhaps related) to the GPU lockup issue that I created a bug report on FreeDesktop.org back in April, but it remains open to this day. This issue has also reportedly affected others, for some even experiencing GPU hangs from the desktop when Compiz is active.
I've hit these Radeon HD 6000 series support problems with the latest components in a variety of configurations and with all Northern Islands / Cayman GPUs at my disposal: Radeon HD 6570, Radeon HD 6870, and Radeon HD 6950.
At least kernel mode-setting seems to be working fine and once fixing up a few bugs the overall support will hopefully be on par with that of the Radeon HD 4000 and Radeon HD 5000 series. The “R600g” driver provides the Radeon HD 6000 series Gallium3D support so most of the code is shared going back to the Radeon HD 2000 series when it comes to this user-space driver.
When this support is fixed up, we will finally be able to deliver open-source benchmarks, but hopefully this is cleaned before the Radeon HD 7000 series launch. This belated support is not a complete surprise when it was only last month that the open-source AMD Fusion driver had stabilized. Further out, we are excited about the Radeon HD 8000 series when there should be a major open-source milestone in that we'll hopefully see on-time open-source Linux support for this hardware right around the time the hardware first ships.