TMS320C6421 RBL ECC issue

tomeko

Hello,

while testing C6421 ROM bootloader in NAND mode I observed unexpected behavior related to NAND ECC:

- single bit error in page data (1/4 of the 2kB page, 512B to be precise) area was corrected (that is OK),

- single bit error in page spare area (in ECC value itself) caused boot failure or booting from next block (if there was a boot copy in next block)

Could anyone confirm this issue? In my test I was damaging bit by programming page second time with 0xFFs value and single bit cleared in place of one that was set in undamaged page - it should be reproduceable.

Exact markings on tested processor:

TMS320C6421ZWT

$NC-83A04Xw

Tested with 1Gbit NAND, device ID = 0xF1 (2kB page).

Could you point me to any other documentation besides spraak5b? I find it not precise in this area, conditions on which bootloader skips block are not documented.

over 10 years ago

0 Shankari G over 10 years ago

TI__Mastermind 43955 points

Hi Tomeko,

1. Is the NAND device used is supported by the TI RBL used? There exist a TI Wiki page which helps determining the compatibility between RBL and NAND devices. http://processors.wiki.ti.com/index.php/Determining_compatibility_between_ROM_Bootloader_(RBL)_and_Raw_NAND_devices

http://processors.wiki.ti.com/index.php/Raw_NAND_ECC#What_are_the_options.3F

Regards,

Shankari

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0 tomeko over 10 years ago in reply to Shankari G

Intellectual 280 points

Thank you for answer.

According to spraak5b this NAND (0xF1 device ID, 2kB page, 128MB) is supported by TMS320C642x bootloader and I'm confirming that device is booting from this NAND. The only problem arises when single bit error appears in spare area (ECC code), not in data area - it should be ignored in this case by RBL, but RBL skips block. Thus single bit error in NAND page renders it unusable (causing boot failure) if it appears in ECC code (4.6% probability and it's hard to fight it with block refreshing as it would require refreshing blocks even if they have no errors).

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TMS320C6421 RBL ECC issue