[i.MX RT1172] How to Set OTFAD ENABLE via eFuse

[Miller]

I cannot find a certain place in the SRM doc that describes how to enable the OTFAD (via eFuse).

Does it mean the OTFADx_KEY_BLOB_EN?

Issue:

I have already set the eFuse USER_KEY5 / key_scramble / key_scramble_align / OTFADx_SCRAMBLE_EN / OTFADx_KEY_BLOB_EN / SRKH / BOOT_CFG1[1] .

Boot Mode uses GPIO Internal Boot.

(SEC_CONFIG / OTFADx_KEY_SEL / BT_FUSE_SEL use default value)

In this case, the processor runs normally if burns the signed image, the processor boots failure if burns the signed and encrypted image.

When the processor runs normally, read the register OTFAD1 and GE/GEM value is 0.

So,  how can I make the GE/GEM to 1?

[Miller · Accepted solution]

If the Config-GPIO already used by another feature, set this fuse to 1 and OTFAD may run normally.

[victorjimenez]

Hello, 

The boot ROM enables Encrypt XiP via OTFAD when the ENCRYPT_XIP_ENGINE fuse (0x970[12]) is 0 and if either of the following conditions is met:

• The ENCRYPT_XIP_EN fuse bit (0x940[1]) is blown.
• The BOOT_CFG_1[1] pin is asserted when the BOOT_CFG settings are sampled from the BOOT_CFG pins.

Regards,
Victor