With the help of hammer, chisel and pile of damns I've managed to make ordinary U-Boot that includes fastboot "server", automatically goes straight into fastboot mode on booting and could be loaded with imx_usb_loader. I've used Yifan Lu's fastboot client
to get idme var and it worked. But I have no desire to overwrite my partitions now (to test flash
Note, that check
command will not return real result (as crc32 checking function was removed to decrease file size).
Of course, I can't say for sure, whether it really does not require bist U-Boot, as I has no serial console access and can't check the log. So sorry for disappointment if it will not work as described.
Report me and I will delete attachment.
(Patch to original U-Boot source will be provided soon, if it really will work; just let me day or two to tidy up that mess of impulsive edits UPD