I am trying to set up the i.MX6UL fuses in way that would completely disable the USB serial download and JTAG functionality. My device normally boots from QSPI flash.
I have set the SDP_DISABLE fuse bit as described in the Reference Manual (0x460) as well as the SDP_READ_DISABLE fuse (0x460) and the SJC_DISABLE fuse (0x460). Disabling the JTAG controller seems to work, but the USB serial download feature is still active even though I have set the "disable" fuses.
Reading the fuses via u-boot I get the following:
$ fuse read 0 6
$ Word 0x00000006: 00160000
Any idea what that might be the case?