Enabling the FIELD_RETURN_LOCK

nemik — Mon, 14 Dec 2020 16:21:26 GMT

Hello,

I am trying to enable the FIELD_RETURN_LOCK bit in OCOTP_SW_STICKY register on my "closed" (fused) imx7dsabresd board.

I verified that I can only unlock OCOTP features by flashing the bootloader to NAND, otherwise it does not work in SDP mode over USB. I verified this by enabling the SRK REVOKE which did work when flashed, but not over SDP.

However nothing I try seems to let me enable the FIELD_RETURN_LOCK bit as described here: https://community.nxp.com/t5/Known-Limitations-and-Guidelines/Field-Return-dependency-on-OCOTP-Module-clock-in-MPU-and-MCU/ta-p/1123766 I'm also not sure why I can't access that document now, but could a couple of weeks ago. There is a cached version here: https://webcache.googleusercontent.com/search?q=cache:kkLTvDfCjUsJ:https://community.nxp.com/t5/Known-Limitations-and-Guidelines/Field-Return-dependency-on-OCOTP-Module-clock-in-MPU-and-MCU/ta-p/1123766+&cd=1&hl=en&ct=clnk&gl=us

I test the OCOTP_SW_STICKY using "md 0x303500B0 1" in U-Boot and always get 0x18 and did manage to get 0x1C when enabling SRK Revoke, but it did not enable FIELD_RETURN.

My board's UID is "000001266e48126a" and I see this running

$ cat /sys/fsl_otp/HW_OCOTP_TESTER0 
0x6e48126a
$ cat /sys/fsl_otp/HW_OCOTP_TESTER1 
0x126

and also when printing it from U-Boot using the tag_serialnr struct.

In my CSF file, I am adding:

[Unlock]
Engine = OCOTP
Features = FIELD RETURN, SRK REVOKE
UID = 0x00, 0x00, 0x26, 0x01, 0x48, 0x6e, 0x6a, 0x12

and different combinations of the UID but can't seem to turn off the FIELD_RETURN sticky bit.

Any help is appreciated. Thank you,

Nemanja Stefanović

Re: Enabling the FIELD_RETURN_LOCK

Yuri — Tue, 15 Dec 2020 05:21:40 GMT

@nemik
Hello,

I've sent You some comments directly.

Regards,
Yuri.

topic Re: Enabling the FIELD_RETURN_LOCK in i.MX Processors

Enabling the FIELD_RETURN_LOCK

Re: Enabling the FIELD_RETURN_LOCK