I've been using an iMX6S on my platform, and have successfully created a signed U-Boot, blown the HAB fuses, and 'closed' the device. But when I perform the same fuse steps on an iMX6UL, I'm unable to close the device. The security fuses themselves (bank 3, word 0-7) read back ok and there are no HAB Events, but when I do 'fuse prog –y 0 6 0x00000002' (to close the device), U-Boot is throwing a 'usage' error.
(NB - I've also first attempted to disable the JTAG with 'fuse prog –y 0 6 0x00100000')
Is the 'close' fuse in a different place on the UL?