AMD's New GPU Kernel Driver Could Be Too Late For Linux 3.19
With Linux 3.18, Airlie started cutting off the DRM-next merge requests early -- around Linux 3.17-rc5~rc6 -- rather than in the past where he's allowed new driver changes to be merged into his -next branch up until the release of the current kernel development cycle. He did this change to try to reduce the number of DRM graphics related regressions and issues that have been somewhat common when upgrading kernels. This change worked out well for Linux 3.18 and so David intends to do the same for Linux 3.19.
As Linux 3.18-rc3 was just released, that means there's just two or three more weeks for new DRM material to be merged into drm-next that wishes to make it into Linux 3.19.
One of the major changes we're looking forward to this fall is for AMD's new unified Linux graphics driver that converges their open-source Radeon and Catalyst driver code. This new AMDGPU Linux driver is expected to see the first bits of kernel code publicly released this autumn, but given that we're now nearing the cutoff for Linux 3.19 DRM merging, it's a bit worrisome that we might not now see the initial AMDGPU driver merged to mainline until at least Linux 3.20 in 2015. Airlie noted in his mailing list post, "AMD new driver, if this was aiming for next merge window you are probably late, since it will require review at a guess."
While the AMDGPU driver is primarily designed for future AMD graphics processors, this delay is a burden for those who but the AMD Radeon R9 285 "Tonga" as it's the first GPU being brought up on the new driver stack and isn't being supported by the current open-source Radeon driver code. As a result, R9 285 owners for now need to use this GCN 1.2 GPU with Catalyst on Linux and have no open choice until AMDGPU premieres.
The R9 285 "Tonga" is stuck waiting on the AMDGPU driver to be published so it can shine on open-source Linux software.
David also mentioned in his message that he's monitoring the new ARM Rockchip DRM driver but first the IOMMU driver needs to be merged somewhere before he can even begin compiling and evaluating this driver for mainline inclusion. Thus it's not known right now whether it will make Linux 3.19.
The atomic mode-setting helper library work is still progressing as another potential feature of DRM in Linux 3.19. David is also looking forward to Exynos patches to allow the Samsung Chromebook to work with the upstream graphics driver. More details in David's post.
One big feature of the DRM subsystem we're looking forward to in Linux 3.19 is initial enablement for Intel's 2015 Skylake graphics.
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