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SubjectRe: [PATCH v7 2/2] mtd: rawnand: meson: add support for Amlogic NAND flash controller
Hi Liang,

Liang Yang <liang.yang@amlogic.com> wrote on Tue, 11 Dec 2018 09:56:25
+0800:

> 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.

A suppose you meant "blank page"? If yes, then you don't need the
helper to check for only-0xFF pages. If the controller tells you if the
page was blank, then just check for that bit.


Thanks,
Miquèl

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