• Karl Beldan's avatar
    mtd: nand: davinci: Reinitialize the HW ECC engine in 4bit hwctl · f6d7c1b5
    Karl Beldan authored
    This fixes subpage writes when using 4-bit HW ECC.
    There has been numerous reports about ECC errors with devices using this
    driver for a while.  Also the 4-bit ECC has been reported as broken with
    subpages in [1] and with 16 bits NANDs in the driver and in mach* board
    files both in mainline and in the vendor BSPs.
    What I saw with 4-bit ECC on a 16bits NAND (on an LCDK) which got me to
    try reinitializing the ECC engine:
    - R/W on whole pages properly generates/checks RS code
    - try writing the 1st subpage only of a blank page, the subpage is well
      written and the RS code properly generated, re-reading the same page
      the HW detects some ECC error, reading the same page again no ECC
      error is detected
    Note that the ECC engine is already reinitialized in the 1-bit case.
    Tested on my LCDK with UBI+UBIFS using subpages.
    This could potentially get rid of the issue workarounded in [1].
    [1] 28c015a9 ("mtd: davinci-nand: disable subpage write for keystone-nand")
    Fixes: 6a4123e5 ("mtd: nand: davinci_nand, 4-bit ECC for smallpage")
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarKarl Beldan <kbeldan@baylibre.com>
    Acked-by: default avatarBoris Brezillon <boris.brezillon@free-electrons.com>
    Signed-off-by: default avatarBrian Norris <computersforpeace@gmail.com>
davinci_nand.c 24 KB