We need to disable JTAG.
How can we disable JTAG in Linux firmware.?
You may use SJC Disable Fuse for this purpose, please find more information about this fuse in the i.MX 8M reference manual chapter 22.214.171.124 SJC Disable Fuse, you may also find more information about this fuse in our Security Reference Manual.
As for the blow fuses procedure you may do this in uboot by using the fuse command:
fuse - Fuse sub-system
fuse read <bank> <word> [<cnt>] - read 1 or 'cnt' fuse words,
starting at 'word'
fuse sense <bank> <word> [<cnt>] - sense 1 or 'cnt' fuse words,
fuse prog [-y] <bank> <word> <hexval> [<hexval>...] - program 1 or
several fuse words, starting at 'word' (PERMANENT)
fuse override <bank> <word> <hexval> [<hexval>...] - override 1 or several fuse words, starting at 'word'
Also, it may be useful to take a look to this thread for more option for blow fuses: https://community.nxp.com/thread/480188?commentID=1161432&et=watches.email.thread#comment
Hope this helps,
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