Pls explain i.mx8 Fuse map Bank/Word mapping to Offset in ref manual

[mobrien]

The values I read from uboot using fuse read command are not corresponding with the default values listed in the i.mx8m mini reference manual.

Is there a better explanation of how to map the offset listed in the ref manual to the bank/word in uboot.

For instance.

Ref Manual states the table on page 849 that offset 0x0400 corresponds to bank 0 word 0 which has a reset value of 0000_0000

When I read this using ">fuse read 0 0 1" in uboot I get feafa9eb

Is there a document that better explains how to translate from the offsets listed in table 6-49 to the bank/word addressing used by the uboot fuse command?

Specifically which bank/word has the BOOT_CFG setting and which bank/word has the M4 disable bits?

[shivanipatel]

Hi mobrien@uaudio.com‌,

Along with Yuri Muhin comment, please find my answer for your below question,

Specifically which bank/word has the BOOT_CFG setting and which bank/word has the M4 disable bits?

Answer: Offset 0x470 to 0x4B0 are for BOOT_CFG setting. And the 8th bit of offset 0x450 which is mapped to OTP Bank1 Word1 (OCOTP_HW_OCOTP_TESTER4) is used to enable/disable the M4 core. However its write access permission is decided from the value of the OTP Bank0 Word0 (OCOTP_HW_OCOTP_LOCK).

Hope this will help you.

Regards,

Shivani

[Yuri]

Hello,

  I hope the following resources help to clarify the issue.

Understanding how to burn eFuses on i.MX8 and i.MX8x families - i.MXDev Blog 

https://www.embeddedartists.com/wp-content/uploads/2020/03/iMX_Howto_Program_Fuses.pdf 

Regards,

Yuri.

[lockit282]

I attempted to burn the field_return fuse on my imx8mm from u-boot. 
1. I made sure the stick-bit was in the proper state

2. I did the csf_fit signing with my device id.  
My device id: 

DAB3DAF3 0F30A209

So I put the following in the csf_spl.txt,
[Unlock]

Engine = OCOTP

Features = FIELD RETURN

UID = 0xf3, 0xda, 0xb3, 0xda, 0x09, 0xa2, 0x30, 0x0f
Questions: Does the Unlock also need to be in the csf_fit file?
Did I use the correct byte order for the UID in the csf file, e.g.:

DAB3DAF3 0F30A209 = 0xf3, 0xda, 0xb3, 0xda, 0x09, 0xa2, 0x30, 0x0f
3.  I installed my signed images with the unlock command in my csf_Spl.txt file

4. I blew the fuse on the imx8mm in uboot : fuse prog -y  8 3 1
Per the Imx8mm manual:

Value of OTP Bank8 Word3 (Field Return)

(OCOTP_HW_OCOTP_FIELD_RETURN)

5. I rebooted and received the following error:
Authenticate image from DDR location 0x401fcdc0...
RNG already instantiated 0x40000003
Error: blob decap job failed 0x2000071a
rpmb_read: decap rpmb key error
rpmb_init: read RPMB error
RPMB init failed!
SPL: failed to boot from all boot devices
### ERROR ### Please RESET the board ###
Note: This board had been secure and booted properly before blowing the field return fuse
I would appreciate any help and pointers as to where I went wrong