This is a theme with the RPi. They generally implement new hardware in their proprietary firmware first, for lack of skills/time to do a proper upstream job of it (or the convience of copy-pasting some vendor code), then pay someone to develop an open-source driver. For example, here is a massive 80 patch series nearing merge for the new display pipeline in the RPi 4:
https://github.com/anholt/linux/wiki/Raspberry-Pi-and-other-...
This is a theme with the RPi. They generally implement new hardware in their proprietary firmware first, for lack of skills/time to do a proper upstream job of it (or the convience of copy-pasting some vendor code), then pay someone to develop an open-source driver. For example, here is a massive 80 patch series nearing merge for the new display pipeline in the RPi 4:
https://patchwork.freedesktop.org/series/73839/