i.MX6q Boot fuse settings

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i.MX6q Boot fuse settings

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shajinas
Contributor I

Hello Nxp Team,

I'm working on a custom platform based out of the i.mx6q Sabresd platform. The software running on the custom platform is based out of Android Pie(P9.0.0_2.2.0-ga) from NXP.

The custom platform was designed to select the boot device based on the boot fuse settings. The BOOT_MODE0 & BOOT_MODE1 are set to 00. I believe the Boot ROM code will decode the value present in the BOOT_CFG1(0x21BC450), BOOT_CFG2(0x21BC460) and BOOT_CFG3(0x21BC470) registers and subsequently look for the u-boot loader on the storage medium.

I was playing around with these registers to set the boot device as the onboard eMMC . I've updated the register (0x21BC450) and (0x21BC460) through the fuse prog commands present in the bootloader. However I was not successful in booting out of eMMC also unable to revert back to default settings.

Please find the steps below which i have carried out

1) Default Value of the BOOT_CFG1 register value before start of the experiment

0x21BC450 = 0x18000030 // Boot from SPI NOR flash

0x21BC460 = 0x00000010 // BT_FUSE_SEL select

U-Boot # md 0x021BC450

021bc450: 18000030 18000030 18000030 18000030

021bc460: 00000010 00000010 00000010 00000010

 

2) Updating the register values

U-Boot # fuse prog -y 0 5 0x00005860

U-Boot # fuse prog -y 0 6 0x00000010

U-Boot # md 0x021BC450

021bc450: 18005870 18005870 18005870 18005870

021bc460: 00000010 00000010 00000010 00000010

 

3) I tried to revert back to the original settings, But unfortunately I was not successful in the process.

U-Boot # fuse prog -y 0 5 0x18000030

U-Boot # fuse prog -y 0 6 0x00000010

U-Boot # md  0x21BC450

021bc450: 18005870 18005870 18005870 18005870

021bc460: 00000010 00000010 00000010 00000010

 

Can you let me know where I went wrong in the process?

It would be really helpful if you can provide pointers on how to revert back to the default settings.

 

Thanks for your time.

 

Thanks

Shajin

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Yuri
NXP Employee
NXP Employee

@shajinas 
Hello,

    It is highly recommended to try first GPIO boot overrides in order to check boot settings,
since the fuses can be burned only once.

Regards,
Yuri.

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