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    SubjectRe: [PATCH v7 2/2] mtd: rawnand: meson: add support for Amlogic NAND flash controller
    On Tue, 11 Dec 2018 09:56:25 +0800
    Liang Yang <liang.yang@amlogic.com> wrote:

    > Hi Miquel,
    >
    > On 2018/12/10 22:50, Miquel Raynal wrote:
    > > Hi Liang,
    > >
    > > Liang Yang <liang.yang@amlogic.com> wrote on Mon, 10 Dec 2018 20:12:39
    > > +0800:
    > >
    > >> On 2018/12/10 19:38, Boris Brezillon wrote:
    > >>> On Mon, 10 Dec 2018 19:23:46 +0800
    > >>> Liang Yang <liang.yang@amlogic.com> wrote:
    > >>>
    > >>>>>> + mtd->ecc_stats.failed++;
    > >>>>>> + continue;
    > >>>>>> + }
    > >>>>>> + mtd->ecc_stats.corrected += ECC_ERR_CNT(*info);
    > >>>>>> + bitflips = max_t(u32, bitflips, ECC_ERR_CNT(*info));
    > >>>>>> + }
    > >>>>>
    > >>>>> Are you sure you handle correctly empty pages with bf?
    > >>>>> >> if scramble is enable, i would say yes here.
    > >>>> when scramble is disabled, i am considering how to use the helper
    > >>>> nand_check_erased_ecc_chunk, but it seems that i can't get the ecc
    > >>>> bytes which is caculated by ecc engine.by the way, nfc dma doesn't send
    > >>>> out the ecc parity bytes.
    > >>>
    > >>> Even if the ECC engine is disabled?
    > >>>
    > >> No.
    > >> When ECC engine is disabled, it can read the ecc parity bytes ; but there is another problem that i need to consider how code struct looks better when reading error with ecc opened and then try to raw read.
    > >> Is there a good idea?
    > >
    > > When reading with ECC enabled, in case of uncorrectable error you
    > > must re-read without ECC, then check if the page is empty or not with
    > > the core helpers (nand_check_erased_*()).
    > >
    > > Is this what you meant?
    > >
    > yes. when uncorrectable ECC error, i need firstly read out the ECC bytes
    > without ECC engine and then use the helper nand_check_erased_ecc_chunk
    > to check if blank page.
    > Of course, the precondition is without scrambler, or the bland page can
    > be detected by meson NFC.

    Yep, raw accessors should disable both the scrambler and the ECC
    engine (see what's done in sunxi_nand.c).

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