Intel's Early Linux 5.10 Graphics Driver Changes Include Tiger Lake HOBL

While the Linux 5.9 kernel cycle is still young and not seeing its formal release until early October or so, Intel's open-source team has already submitted to DRM-Next their first batch of feature changes desired for Linux 5.10.

This is just the first of several pull requests expected of graphics/display updates for Intel hardware expected for Linux 5.10. Among the material in this initial pull request are:

- HOBL is added for Tiger Lake / Gen12+ hardware. HOBL is short for "Hours of Battery Life" and is about utilizing an optimized voltage swing table to use less power in conjunction with capable motherboards and eDP panels that can operate at the lower voltage. Intel's patent application for HOBL previously indicated as much as 20~30% CPU/SoC power saving, but presumably we'll learn more once Tiger Lake formally launches.

- While HOBL is a win for Tiger Lake, at the same time Intel is temporarily disabling frame-buffer compression (FBC) for Tiger Lake. FBC was found to cause some random under-run issues and thus for now they are disabling this feature that helps conserve memory bandwidth and power savings. Sad that even with Tiger Lake they are still hitting FBC issues as back during the early Skylake days that was quite a common problem with their Linux driver and took some time until FBC was good enough for enabling by default.

- Linux 5.10 also brings many Tiger Lake display fixes and improvements, particularly around Type-C handling and DisplayPort compliance.

- Synchronization object timeline object support is exposed to user-space so that handles and timeline points can be specified via the execbuf interface. Synchronization objects are used by Intel's Vulkan driver around VK_KHR_timeline_semaphore and similar functionality.

- Display work on the Intel Rocket Lake support initially introduced in Linux 5.9. Rocket Lake isn't coming until next year and thus expect the Linux driver support to stabilize over the next few cycles.

- DisplayPort link training improvements.

More details on the initial Intel i915 DRM driver changes for Linux 5.10 via the PR