I discovered that the K4 main partition has a strange mix of old K3 eink driver and new K5 8-bit framebuffer. The K4 diags partition uses the same new eink driver as the K5.
The side effect is that when booted from main, the K4 displays NEGATIVE images (swapped black and white) for dithered images.
For now (until I finish my complete redesign to fix this), on a K4 you should use diags SSH to run the eink demos (including demo.c in my tcc package).
The old eink drivers do a full-flash clear for "eips -c", but this does a non-flash clear for new eink drivers (faster, but leaves ghosting). New eink drivers do a full-flash clear for "eips -c -f", but this also displays "-f" on the screen for old eink drivers. Here is a simple command for all eink kindles that does full-flash clear (or two) with no garbage left on the display: "eips -c -f;eips -c". To avoid the extra flash on old eink drivers, you would need a more complicated test for which version of device driver (and eips comman) is being used.
EDIT: Okay, here is the "smarter" full-flash clear for all eink kindles:
eips|grep "\-t"&&eips -c -f;eips -c
Hmm... The strange K4 main partition eink support has a new eips command but old drivers, so it does full-flash clears for both "eips -c" and for "eips -c -f". Oh, well... enough time burned on this. Just live with it (or use K4 diags for eink stuff).
