imx8mp manufacture mode, which SDHC ports are available? Other options to boot from SDHC1?

[srainey]

I have a custom board with the imx8mp currently in the initial bringup stage. We're having difficulties because of our boot setup. We have an unprogrammed eMMC attached to USDHC3 and connections for an SD card attached to USDHC1. 

1. Since SDHC1 is not selectable via the boot mode pins, we are hoping that the "manufacture mode" will be able to utilize this port, but there is limited information that I see in the PRM about this mode. Can anyone confirm that SDHC1 boot will be attempted in manufacture mode?

2. We also see that it's possible to use the boot mode fuses to boot SDHC1. If SDHC1 is not available via manufacture mode, is there a way we can set the fuse without having any boot media? We do have a connection to the JTAG lines, but we have not been successful in accessing the DAP port with no boot media present. Is this a possibility?

[AldoG · Accepted solution]

Hello,

1> No, manufacture mode will scan uSDHC2 port for a valid image.

2> Yes, actually if device enter serial download, and in your custom board you have access to USB for SDP you may use UUU for this, which will download uboot and use fuse command to blow fuses:

The U-Boot fuse command is capable of reading and writing the efuses.

=> fuse
fuse - Fuse sub-system

Usage:
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,
    starting at 'word'
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'

Best regards,
Aldo.