i.MX7D signed image download with UUU

[#1]

Symptoms

Downloading a signed mage using UUU on i.MX 7D TO 1.3 (latest) silicon leads to authentication errors in an open chip and boot failure in closed chip.

Diagnosis

Reasoning behind this issue is that the TO1.3 has an Errata e11166 which disallows first 4K of the OCRAM memory region to be used for the bootable image. Since DCD is loaded at the start of OCRAM, the SDP download of the boot image fails.

Solution

Signing boot image

While building the u-boot bootloader, the u-boot build log indicates the DCD address at which DCD will be downloaded, however, this address is incorrect and should be 0x911000 due to the Errata indicated above.

$ cat u-boot-dtb.imx.log
Image Type:   Freescale IMX Boot Image
Image Ver:    2 (i.MX53/6/7 compatible)
Mode:         DCD
Data Size:    610400 Bytes = 596.09 KiB = 0.58 MiB
Load Address: 877ff420
Entry Point:  87800000
HAB Blocks:   0x877ff400 0x00000000 0x00092c00
DCD Blocks:   0x00910000 0x0000002c 0x000001c4

When adding the DCD Block in CSF, make sure to fix the DCD address (if this is fixed in your u-boot version, ignore this step)

CSF:

[Authenticate Data]
        Verification index = 2
        Blocks = 0x877FF400  0x000  0x81C00 "u-boot.bin", \
                 0x00911000  0x2c   0x1C4   "u-boot.bin"

UUU command to download image:

After the boot image is signed properly the image can be downloaded using UUU with following command:

sudo ./uuu SDP: boot -f u-boot-signed.bin -dcdaddr 0x00911000

Using this command ensures the boot image is downloaded at the correct DCD address and thus the image can be authenticated properly.

This is also updated in UUU wiki: