raspberry pi hdtft 800x480

so, i've got a raspberry pi with an 800x480 screen, and i can't get it to work with alpine.

the docs for raspbian are here: http://www.raspberrypiwiki.com/index.php/3.5_inch_TFT_800x480@60fps

i've tried every permutation of everything i can think of, and can't get it to work. for raspbian it's just drop a dt-blob.bin file in /boot, and add a few lines to config.txt.

anybody have ideas?

thanks!