ECC validation of Sector information RRS feed

  • Question

  • I am wondering why FMD drivers never verifies sector information part in the FMD NAND flash driver?

    The Sector data part (512 byte in my case) is checked with ECC and corrected if any bit-error occurs but the spare part (16 byte in my case) for every sector where the sector information is stored is not verified for errors. If a bit error occurs in that part it will give strange behavior of the flash disk as I see it.

    Is there anything I am missing here?

    Hans Skytt Steffensen

    Friday, September 10, 2010 9:47 AM

All replies

  • It depends on FMD driver implementation. Check Samsung S3C6410 FMD driver and get evidence that spare part has ECC too.

    P.S. I've checked FMD sources obtained from CE 7, but it seems CE 6 driver looks similar.

    Friday, September 10, 2010 12:07 PM
  • Depends on your hardware (the NAND flash controller in the CPU).  Some controllers cover the spare area, and others do not.  If it does, then the flash FMD needs to ensure that it is implemented properly in software.  Note that when the spare area is covered by ECC it can no longer be marked dirty without causing an ECC error.  That has to be accounted for in the flash driver as well.

    You're right though; the extra bits are just bits and those could fail as well so they should be protected.  Unlike the data bits they are not all used so the likely hood of a failure hitting an area that matters is less, but not zero.

    Dean Ramsier eMVP BSQUARE Corporation
    Friday, September 10, 2010 1:45 PM