Nouveau Preparing To Finally Enable Atomic Mode-Setting By Default

In addition to the Nouveau kernel driver unblocking Vulkan Video H.264 support for the Mesa NVK driver, another feature change on the way is this open-source NVIDIA Linux driver finally preparing to enable atomic mode-setting by default. Nouveau has long supported atomic mode-setting but it hasn't been enabled by default. Atomic mode-setting allows for user-space compositors/programs to pass complete hardware configurations to the kernel for committing as a single atomic transaction. Atomic mode-setting can in turn mean less screen flickering and more reliable mode-setting experience on the modern Linux desktop. Most Linux desktop software supports atomic mode-setting and the major open-source DRM kernel drivers have long supported it. Lyude Paul of Red Hat has been working through the patches for enabling atomic mode-setting by default with the Nouveau driver. This affects the NVIDIA NV50 / GeForce 8 series and newer. Lyude commented with the latest patches enabling Nouveau atomic KMS by default: "Nouveau is one of the very few modern hardware drivers in the kernel that doesn't have atomic modesetting enabled by default, in part because when it was originally written by Ben there wasn't much in the way of good atomic modesetting clients to actually test things out with. Nowadays however, atomic modesetting is very much the norm - and support in userspace for non-atomic drivers is starting to bitrot a bit - leading to its own set of issues. At the same time, many of those issues are fixed by just turning on atomic in nouveau. Plus, I've been running nouveau with atomic modesetting on by default for most of the machines I work on, and I've already fixed quite a number of issues to the point where things seem quite stable (excluding a single screen flashing bug on my desktop, which I am not particularly convinced has anything to do with atomic modesetting). This patch series enables atomic modesetting by default, at least for NV50 and newer. NV04 is left unchanged, as atomic modesetting was never implemented for it. This series also enforces leaving atomic modesetting disabled on <NV50, and adds the value of nouveau.atomic to our kernel debug output." Given the current timing, it's probably unlikely this will get picked up in time for the Linux v7.3 cycle but hopefully this default change will land soon after.