I just upgraded my K5(Touch) to 5.1.0, and now the ioctl() call for eink updates DOES NOT WORK! What's up with that? That was a major find, and now they broke it? Bummer... I will have to find a workaround to make it work again.
EDIT: At least amazon did not break the eink update ioctl() in diags mode (yet). The only flag I guessed on was setting "MARKER" to 1 because value 0 did not work. Perhaps I have to find a different value for that. Any ideas what value to use?