Software verification of ECC on OMAP35x

steve miller4

I have a client with continuous issue with ECC corrections on NAND flash on their product which uses OMAP35x. We have implemented scrubbing on the flash but that seems to have limited success.

To thoroughly test out a factory flashing tool, u-boot and linux drivers properly, I would like to use/write a utility to exercise specific single and multiple bit ECC corrections (in this case either 8bit BCH or Hamming single bit) to ensure that the software is handling the corrections properly.

Has anyone written a tool like this before? I would prefer to have a third party calculation of the ECC codes rather than use the hardware itself to generate/verify its own codes.

over 12 years ago

0 Cvetolin Shulev-XID over 12 years ago

TI__Guru 65405 points

Hi Steve,

I couldn't suggest you source code for ECC correction on NAND flash but I'll point you some links to information about ECC which should be useful:

1. Technical Reference Manual section 11.1.5.14.3 ECC Calculator

http://www.ti.com/lit/ug/spruf98x/spruf98x.pdf

2. Pay attention on the Silicon Errata - Advisory 3.1.1.183 GPMC Has Incorrect ECC Computation for 4-Bit BCH Mode.

http://www.ti.com/lit/er/sprz278f/sprz278f.pdf

3. Look at the following articles:

Raw NAND ECC

http://processors.wiki.ti.com/index.php/Raw_NAND_ECC

Error correction user guide:

http://processors.wiki.ti.com/index.php/Error_Correction_User_Guide

Tsvetolin Shulev

0 steve miller4 over 12 years ago in reply to Cvetolin Shulev-XID

Prodigy 140 points

Thanks Tsvetolin

Those are useful documentation links. However this is a mature product in the field that is currently uses BCH8 on its flash and we have witnessed corrections (applied by software) to the data read from failed units.

So I would like to test out this correction to make sure that the drivers are working as we would expect. There are numerous commits regarding NAND driver fixes in Arago (which we are not currently using) and I would like a test to verify our drivers.

My thoughts are that I could modify a MTD utility (we are using 2.6.32) to write specific OOB data for a particular page and force a specific correction.

Has anyone done this level of testing before and could they share it with me?

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Software verification of ECC on OMAP35x