fuse prog

[lifusong]

Dear .

the uboot(imx6q-2014.04) Provided a command  fuse

like as  fuse read 4 2 2 will show MAC

and fuse prog 4 2 0x11223344

the question.  I can read mac info through command fuse read 4 2 2.

but can't set  through command fuse prog 4 2 0x11223344

anybody can help me.

[jith]

Hi,

Is it possible fuse only the required bit. Example is like I need to fuse the 2nd bit  only for a specific configuration and remaining bits are not required for my requirement. Is there any option/procedure to program fuse to meet mentioned requirement.

[igorpadykov]

yes it is possible to fuse only the required bit.

Best regards
igor

[jith]

Hi Igor,

Could you please provide the procedure to fuse one bit?

I am not sure on the procedure.Do we need to keep default value of the another non-required bit?

[igorpadykov]

procedure is the same, just provide value for fusing which

differs by one bit compared with existing.

Best regards
igor

[davidpatton]

So if I understand correctly, this is like programming flash, on a bit-wise basis; a 0 can be changed to a 1, but a 1 cannot be changed to a 0, without an erase cycle, however in the case of OTP, there is no erase cycle. In either case, writing a 0 to a 0 does nothing.

Is this where the OCOTP_LOCK register comes into play? Once I set the appropriate BOOT_CFG and MAC address eFuses, I need to set the lock bits to remove the possibility of setting these to all 1's?

[igorpadykov]

> I need to set the lock bits to remove the possibility of setting these to all 1's?

right

[davidpatton]

How does one set the OCOTP_LOCK register? The reference manual, 44.5.9, shows this register as read-only.

[igorpadykov]

Hi li

fuses are one time programmable registers, they can not be reprogrammed to another

values. For fuse blow procedure one can refer to below link

Q&A: How to program i.MX6 eFUSE?

https://community.freescale.com/docs/DOC-95458

Best regards

igor

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[lifusong]

Dear igorpadkov.

  you said fuses are one time programmable registers, they can not be reprogrammed to another

but this link Re: MAC fuses lock can re-set the mac .

can you tell me the reason?

by the way,my board is imx6q.

thanks.

[lifusong]

i had check OCOTP_LOCK[9:8] == 00b  means writing shadow and OTP fuse is enabled.

i try to modify this register with command fuse prog 0 0 20220302 ,don't have any effect.

fuse read 0 0 get the value is 0x20220002

[BiyongSUN]

fusong,

Some fuse may burned already. the fuse is OTP cannot burn again.

[lifusong]

Dear BiyongSUN .

thanks for your help.  if i write error value into OCOTP_MAC0 and OCOTP_MAC1 how to modify to right value.

and I try to fuse prog  4 2 0x11eeddff on other board.and still can't wirte value to OCOCP_MAC0.

the other board OCOTP_MAC0 OCOTP_MAC1 is zero.

[BiyongSUN]

you can try it in the linux using echo command.

/sys/fsl_otp

             
Use echo command to burn the fuse.

Ex:
echo 0x00006200 > /sys/fsl_otp/HW_OCOTP_GP1

Still need to reminder you the fuse is OTP.

[lifusong]

is the /sys/fsl_otp/HW_OCOTP_xxxx driver ok?

the HW_OCOTP_LOCK = 0x20220302 (I don't know reason this value chang to 0x20220302 form 0x20220002, I only at uboot command try fuse prog command).

I try to run "echo 0x20220002 > /sys/fsl_otp/HW_OCOTP_LOCK" many times.

and the HW_OCOTP_LOCK still is 0x20220302.

so i try to run "echo 1 > /sys/fsl_otp/HW_OCOTP_LOCK" and found this value had been changed to eaba7f02

what is the reason? how can fill right value to HW_OCOTP_XXXX.

[lifusong]

and before run fuse prog 4 2 xxxx.

the HW_OCOTP_MAC0 and MAC1 is zero.

I try to change this value and use command "echo 0x11223344 >/sys/fsl_otp/HW_OCOTP_MAC0",and can't change this value.

but echo 1 > /sys/fsl_otp/HW_OCOTP_MAC0 will change this value to 0xd3ee7bf5.I don't know the reson ,why this value will change to 0xd3ee7bf5,command means write one to HW_OCOTP_MAC0.

[BiyongSUN]

to burn the fuse, you need to do bitwise.

the 0s could not become 1s.

[lifusong]

Dear Biyong.

  so,how to reset the board to factory. (reset to not burn status)

[BiyongSUN · Accepted solution]

We have put here lots of times.

It is OTP.

only can progrem once.

Can not return back.

Please check the following webpage

OTP - Wikipedia, the free encyclopedia

[BiyongSUN]

FInd one board has not been burned fuse to try mac address

OTP - Wikipedia, the free encyclopedia

[lifusong]

please see below info.

root@sabresd_6dq:/ # cat /sys/fsl_otp/HW_OCOTP_MAC0

0xd3ee7bf5

root@sabresd_6dq:/ # cat /sys/fsl_otp/HW_OCOTP_LOCK                        

0xeaba7f02

root@sabresd_6dq:/ # echo 1 0x20220002 > /sys/fsl_otp/HW_OCOTP_LOCK          

root@sabresd_6dq:/ # cat /sys/fsl_otp/HW_OCOTP_LOCK                        

0xeaba7f03

root@sabresd_6dq:/ # echo 1 > /sys/fsl_otp/HW_OCOTP_LOCK                    

root@sabresd_6dq:/ # cat /sys/fsl_otp/HW_OCOTP_LOCK                        

0xeaba7f03

root@sabresd_6dq:/ # echo 2 0x20220002 > /sys/fsl_otp/HW_OCOTP_LOCK        

root@sabresd_6dq:/ # cat /sys/fsl_otp/HW_OCOTP_LOCK                        

0xeaba7f03

root@sabresd_6dq:/ # echo 1 0x20220002 > /sys/fsl_otp/HW_OCOTP_LOCK        

root@sabresd_6dq:/ # cat /sys/fsl_otp/HW_OCOTP_LOCK                        

0xeaba7f03

root@sabresd_6dq:/ # echo 0x20220002 > /sys/fsl_otp/HW_OCOTP_LOCK          

root@sabresd_6dq:/ # cat /sys/fsl_otp/HW_OCOTP_LOCK                        

0xeaba7f03

root@sabresd_6dq:/ #