When it comes to today's complex RGB lighting for PC peripherals and the like it's mostly been left up to user-space. With most RGB devices interfacing via USB, it's been up to Linux user-space projects like OpenRGB, OpenRazer, etc, to implement their RGB lighting controls as needed. But as RGB lighting use continues to grow in the PC space for better or worse, there's an increasing need for a kernel API to handle complex RGB devices. Such an API is currently being devised.

Werner Sembach with TUXEDO Computers has been working on kernel handling for complex RGB devices. The reason for this is some RGB hardware not being exposed to user-space such as some notebook keyboard backlights only being controlled via WMI. The current Linux kernel interfaces aren't suitable for complex RGB devices such as with per-key lighting controls, different lighting modes, etc. Sembach has been discussing with kernel developers and the OpenRGB maintainers over a suitable interface for the kernel.

Those interested in this effort to enhance the Linux kernel support for complex RGB devices and ultimately for TUXEDO's work on per-key RGB lighting controls on Linux, see this kernel mailing list thread and the OpenRGB discussion for the current thinking on the kernel proposal.