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    SubjectRe: [PATCH v6 0/6] mtd: rawnand: support MT29F1G08ABAFAWP-ITE:F
    On Fri, 6 Jul 2018 21:27:20 +0200
    Boris Brezillon <boris.brezillon@bootlin.com> wrote:

    > On Mon, 25 Jun 2018 10:44:42 +1200
    > Chris Packham <chris.packham@alliedtelesis.co.nz> wrote:
    >
    > > Hi,
    > >
    > > I'm looking at adding support for the Micron MT29F1G08ABAFAWP-ITE:F chip
    >
    > Hm, it's even worse than I thought. The model name does not include the
    > -ITE suffix (E means ECC can't be disabled), which means we have no way
    > to detect the version with forced on-die ECC.
    >
    > I see 2 solutions to this problem:
    > 1/ Bean provides us a solution to reliably detect when ECC can be
    > de-actived and when it can't
    > 2/ We only ever expose 64 bytes of OOB to the user and consider that
    > ECC can be disabled, even if it can't in reality
    >

    After reading the doc again, I forgot one thing you can try before
    deciding to go for option #2.

    8th bit in byte 5 of READID's result encodes whether the on-die ECC
    state (enabled or not). I remember we had a discussion with Bean where
    he told us this was a runtime status reflecting the on-die ECC state,
    which is crazy, since READID might return different values depending on
    the NAND state, and most of the code in the core assumes READID
    provides a fixed ID that encodes the chip characteristics/capabilities,
    not its state.

    Anyway, if this bit is actually reflecting the on-die ECC state and
    on-die cannot be disabled on your chip, it should stay at 1 even after
    you have sent the SET_FEATURES(DISABLE_ECC) command. Let's hope this
    works as I expect, otherwise we're back to option #2 until Bean suggest
    something else.

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