Intel's Linux Graphics Driver To Enable Atomic Support By Default

The patch landed in Intel's drm-intel-next-queued branch this week for enabling atomic support by default on the hardware platforms where it's fully supported.

Following this mailing list discussion, atomic support is now being turned on by default for the Intel Linux DRM driver while it's disabled-by-default support has been in good shape since Linux ~4.9. Though due to the timing of this change-over, this looks like it will be a change for Linux 4.12 as Intel's 4.11 DRM feature work is already over with the 4.11 merge window being imminent.

Atomic mode-setting allows setting output modes more cleanly by either being able to succeed or fail in one-go while also being able to test a desired mode in advance of the operation, reducing possible flickering situations while also being quicker. Some Wayland compositors have already implemented atomic support in their code. With Enlightenment, using atomic mode-setting and nuclear page-flipping can cause "buttery smoothness" and "perfect rendering". The change has atomic support enabled by default for Gen5 hardware and newer (Ironlake+) while Valleyview and Cherryview watermarks still need to be fixed. Those wanting to force enable it on these other platforms or with a current Linux kernel release can set i915.nuclear_pageflip=1.

When it comes to atomic support on the other major DRM drivers, ignoring the smaller drivers that have it working, the Nouveau driver introduced its atomic mode-setting support in the Linux 4.10 kernel. AMD's atomic support is being worked on with DC/DAL, so their AMDGPU atomic support will come once that massive display refactoring lands; I haven't seen any atomic work happening for the Radeon DRM driver.