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AM3505 NAND ECC error

oyvindbjo
Prodigy 115 points
Other Parts Discussed in Thread: AM3505

Hi

We are using an AM3505 connected directly to a MT29F4G16ABBDAHC Micron NAND flash through the GPMC bus. There is no problem loading, booting and running x-loader, u-boot, linux and fs.  But when I try the mtd_subpagetest.ko test module (done with TFTP and NFS boot), it gives mee a few ECC errors that are corrected before finally aborting on uncorrectable, more than 1 bit error, faults. The errors is not necessarily on the same pages each time. The same test does not fail on the am3517evm board. Theese tests have been done with the 03.00.00.05 release with SW ECC.

I've also tried the 04.02.00.07 release with HW ECC, but the mtd_subpagetest.ko fails on both the am3517evm and our custom board. The mtd_pagetest.ko runs without problem on am3517evm but finishes with errors on our custom board.

I 've tried to adjust the GPMC bus timing to make it considerably slower, but with no difference.

 

Any help or suggestions would be appreciated.

Øyvind

 

 

 

  • 0
    Prodigy 115 points

    After some more testing we found out that the NAND on the eval board needs at least 1 bit ECC while the one on our board needs at least 4 bit ECC. And apparently our flash has several "bad bits" from the start, thus giving us ECC errors when running mtd_subpagetest. We were using the 03.00.00.05 release which only supports 1 bit ECC. The solution is to use a later release and enable 4 bit ECC.