https://www.mobileread.com/forums/sho...d.php?t=175632 post #13 has geekmaster saying:
"In new (unfinished) code, I using double-buffered display updates. I am NOT writing directly to the framebuffer, but instead to a temp copy of the framebuffer. Then just before the update call I quickly COPY my temp copy to /dev/fb0. This prevents the eink drivers from getting all "confused" because we are writing to the framebuffer while it is trying to use it. This should increase the speed without causing extra annoying display "tearing" artifacts."
It seems a clever C programmer could use some code like this to capture the page, rotate it, and write it back? I would think it would be a pretty quick update of each page.
How to do that is WAAAAY beyond me!