So, https://github.com/slonopotamus/n8x0.../modern-kernel contains current HW status. Most important missing bit is TSC2301 that provides sound/touchscreen/keypad for N800. Also, I talked to mb__ (author of kernel patches) from #openwrt-devel @FreeNode, he said charging driver isn't finished yet, but he's working on it. Also, he's working on sound for N810 (he has one). Meanwile, I'll try to hack on TSC2301 support (though don't expect high chances of success since I'm not a kernel programmer).