The xf86-video-intel Zombie Driver Finally Flips On TearFree To Avoid Tearing
Most users and Linux distributions have transitioned to using the xf86-video-modesetting driver when running Intel graphics on an X.Org Server rather than the xf86-video-intel driver that is effectively in a zombie state. The xf86-video-intel driver hasn't even received any work for the latest Intel graphics hardware generations but it continues seeing random commits here and there -- most of that work led by Intel's Chris Wilson who spearheaded the design of their 2D SNA "SandyBridge New Acceleration" architecture that is to be their default with the elusive xf86-video-intel 3.0 release.
The change this week is enabling "TearFree" functionality by default. The change is enabling TearFree functionality by default for Broadwell/Gen8 graphics and newer. Chris noted, "When there is ample memory bandwidth and we are not fighting for global resources, enable TearFree by default. Avoiding tearing is much more pleasant (for direct rendering where the source itself is not being synchronized to vblank) at negligible power cost; just doubles the memory footprint of scanout."
TearFree has long been an X.Org configuration option for this driver in an effort to reduce tearing when SNA acceleration is enabled. It works out well but due to bandwidth requirements and issues coming up on the likes of Sandy Bridge through Haswell, it hasn't been enabled by default... But as we roll into 2021 and still no signs of a stable release coming for the Intel DDX, at least the change has been made for their driver to flip this on for Broadwell and newer. It's about time.
Anyone still running the Intel DDX (xf86-video-intel) driver?— Phoronix (@phoronix) December 18, 2020