Bootlin has some very nice introductory training materials online: https://bootlin.com/doc/training/linux-kernel/ https://bootlin.com/doc/training/linux-kernel

Bootlin has some very nice introductory training materials online: https://bootlin.com/doc/training/linux-kernel/ https://bootlin.com/doc/training/linux-kernel/ https://bootlin.com/docs/ https://bootlin.com/docs/ Allwinner SoC used in PinePhone has a longstanding community around it organized around http://linux-sunxi.org/ http://linux-sunxi.org/ There are a lot of materials, including datasheets there, etc. https://wiki.pine64.org/index.php/PinePhone https://wiki.pine64.org/index.php/PinePhone wiki also has a lot of information. #pinedev at freenode is where the kernel development discussion happens, so feel free to join there.