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Groups > linux.kernel > #1534722
| From | Boris Brezillon <boris.brezillon@free-electrons.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 15/39] mtd: nand: denali: improve readability of handle_ecc() |
| Date | 2016-12-02 09:00 +0100 |
| Message-ID | <sJQVh-HL-19@gated-at.bofh.it> (permalink) |
| References | <sHPAd-1yq-5@gated-at.bofh.it> <sHPJU-1GL-21@gated-at.bofh.it> <sI9Sh-66y-1@gated-at.bofh.it> <sJNDX-739-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Fri, 2 Dec 2016 13:26:27 +0900
Masahiro Yamada <yamada.masahiro@socionext.com> wrote:
> Hi Boris,
>
>
> 2016-11-28 0:42 GMT+09:00 Boris Brezillon <boris.brezillon@free-electrons.com>:
> >> + if (err_byte < ECC_SECTOR_SIZE) {
> >> + struct mtd_info *mtd =
> >> + nand_to_mtd(&denali->nand);
> >> + int offset;
> >> +
> >> + offset = (err_sector * ECC_SECTOR_SIZE + err_byte) *
> >> + denali->devnum + err_device;
> >> + /* correct the ECC error */
> >> + buf[offset] ^= err_correction_value;
> >> + mtd->ecc_stats.corrected++;
> >> + bitflips++;
> >
> > Hm, bitflips is what is set in max_bitflips, and apparently the
> > implementation (which is not yours) is not doing what the core expects.
> >
> > You should first count bitflips per sector with something like that:
> >
> > bitflips[err_sector]++;
> >
> >
> > And then once you've iterated over all errors do:
> >
> > for (i = 0; i < nsectors; i++)
> > max_bitflips = max(bitflips[err_sector], max_bitflips);
>
>
> I see.
>
> For soft ECC fixup, we can calculate bitflips
> for each ECC sector, so I can fix the max_bitflips
> as the core framework expects.
>
> For hard ECC fixup, the register only reports
> the number of corrected bit-flips
> in the whole page (sum from all ECC sectors).
> We cannot calculate max_bitflips, I think.
>
That's unfortunate. This means you'll return -EUCLEAN more quickly
(which will trigger UBI eraseblock move), since the NAND framework is
basing its 'too many bitflips' detection logic on the max_bitflips per
ECC chunk and the bitflips threshold (by default 3/4 of the ECC
strength).
That doesn't mean it won't work, you'll just wear your NAND more
quickly :-(.
ITOH, doing max_bitflips = nbitflips / nsteps is not good either,
because the bitflips might be all concentrated in the same ECC chunk,
and in this case you really want to return -EUCLEAN.
>
>
> BTW, I noticed another problem of the current code.
>
> buf[offset] ^= err_correction_value;
> mtd->ecc_stats.corrected++;
> bitflips++;
>
> This code is counting the number of corrected bytes,
> not the number of corrected bits.
>
>
> I think multiple bit-flips within one byte can happen.
Yes.
>
>
> Perhaps, we should add
>
> hweight8(buf[offset] ^ err_correction_value)
>
> to ecc_stats.corrected and bitflips.
>
Looks good.
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[PATCH 00/39] mtd: nand: denali: 2nd round of Denali NAND IP patch bomb Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
[PATCH 09/39] mtd: nand: denali: fix erased page check code Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
Re: [PATCH 09/39] mtd: nand: denali: fix erased page check code Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-11-27 16:30 +0100
Re: [PATCH 09/39] mtd: nand: denali: fix erased page check code Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-12-02 05:40 +0100
Re: [PATCH 09/39] mtd: nand: denali: fix erased page check code Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-12-02 09:00 +0100
[PATCH 22/39] mtd: nand: denali_dt: remove dma-mask DT property Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
Re: [PATCH 22/39] mtd: nand: denali_dt: remove dma-mask DT property Rob Herring <robh@kernel.org> - 2016-12-01 17:00 +0100
[PATCH 29/39] mtd: nand: denali: refactor multi NAND fixup code in more generic way Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
[PATCH 28/39] mtd: nand: denali: move multi NAND fixup code to a helper function Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
Re: [PATCH 28/39] mtd: nand: denali: move multi NAND fixup code to a helper function Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-11-27 17:30 +0100
Re: [PATCH 28/39] mtd: nand: denali: move multi NAND fixup code to a helper function Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-30 07:10 +0100
Re: [PATCH 28/39] mtd: nand: denali: move multi NAND fixup code to a helper function Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-11-30 09:10 +0100
[PATCH 15/39] mtd: nand: denali: improve readability of handle_ecc() Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
Re: [PATCH 15/39] mtd: nand: denali: improve readability of handle_ecc() Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-11-27 16:40 +0100
Re: [PATCH 15/39] mtd: nand: denali: improve readability of handle_ecc() Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-11-27 16:50 +0100
Re: [PATCH 15/39] mtd: nand: denali: improve readability of handle_ecc() Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-12-02 05:30 +0100
Re: [PATCH 15/39] mtd: nand: denali: improve readability of handle_ecc() Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-12-02 09:00 +0100
[PATCH 18/39] mtd: nand: denali: move denali_read_page_raw() above denali_read_page() Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
Re: [PATCH 18/39] mtd: nand: denali: move denali_read_page_raw() above denali_read_page() Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-11-27 17:20 +0100
Re: [PATCH 18/39] mtd: nand: denali: move denali_read_page_raw() above denali_read_page() Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-30 07:20 +0100
[PATCH 37/39] mtd: nand: denali: support "nand-ecc-strength" DT property Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
Re: [PATCH 37/39] mtd: nand: denali: support "nand-ecc-strength" DT property Rob Herring <robh@kernel.org> - 2016-12-01 17:20 +0100
[PATCH 23/39] mtd: nand: denali_dt: use pdev instead of ofdev for platform_device Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
[PATCH 36/39] mtd: nand: denali: allow to use SoC-specific ECC strength Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
[PATCH 02/39] mtd: nand: denali: remove unused CONFIG option and macros Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
[PATCH 30/39] mtd: nand: denali: set DEVICES_CONNECTED 1 if not set Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
[PATCH 27/39] mtd: nand: denali: do not set mtd->name Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
[PATCH 35/39] mtd: nand: denali: calculate ecc.strength and ecc.bytes generically Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
[PATCH 39/39] mtd: nand: denali_dt: add compatible strings for UniPhier SoC variants Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
Re: [PATCH 39/39] mtd: nand: denali_dt: add compatible strings for UniPhier SoC variants Rob Herring <robh@kernel.org> - 2016-12-01 17:10 +0100
Re: [PATCH 39/39] mtd: nand: denali_dt: add compatible strings for UniPhier SoC variants Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-12-02 04:00 +0100
Re: [PATCH 39/39] mtd: nand: denali_dt: add compatible strings for UniPhier SoC variants Rob Herring <robh@kernel.org> - 2016-12-02 17:30 +0100
Re: [PATCH 39/39] mtd: nand: denali_dt: add compatible strings for UniPhier SoC variants Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-12-03 03:50 +0100
Re: [PATCH 39/39] mtd: nand: denali_dt: add compatible strings for UniPhier SoC variants Marek Vasut <marek.vasut@gmail.com> - 2016-12-03 04:00 +0100
Re: [PATCH 39/39] mtd: nand: denali_dt: add compatible strings for UniPhier SoC variants Dinh Nguyen <dinh.linux@gmail.com> - 2016-12-03 23:10 +0100
Re: [PATCH 39/39] mtd: nand: denali_dt: add compatible strings for UniPhier SoC variants Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-12-05 04:40 +0100
Re: [PATCH 39/39] mtd: nand: denali_dt: add compatible strings for UniPhier SoC variants Marek Vasut <marek.vasut@gmail.com> - 2016-12-05 04:50 +0100
Re: [PATCH 39/39] mtd: nand: denali_dt: add compatible strings for UniPhier SoC variants Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-12-05 05:20 +0100
Re: [PATCH 39/39] mtd: nand: denali_dt: add compatible strings for UniPhier SoC variants Marek Vasut <marek.vasut@gmail.com> - 2016-12-05 05:30 +0100
Re: [PATCH 39/39] mtd: nand: denali_dt: add compatible strings for UniPhier SoC variants Dinh Nguyen <dinh.linux@gmail.com> - 2016-12-05 22:00 +0100
Re: [PATCH 39/39] mtd: nand: denali_dt: add compatible strings for UniPhier SoC variants Marek Vasut <marek.vasut@gmail.com> - 2016-12-05 22:50 +0100
Re: [PATCH 39/39] mtd: nand: denali_dt: add compatible strings for UniPhier SoC variants Dinh Nguyen <dinguyen@kernel.org> - 2016-12-05 23:40 +0100
[PATCH 12/39] mtd: nand: denali: return 0 for uncorrectable ECC error Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
[PATCH 31/39] mtd: nand: denali: remove meaningless writes to read-only registers Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
[PATCH 32/39] mtd: nand: denali: remove unnecessary writes to ECC_CORRECTION Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
[PATCH 01/39] mtd: nand: allow to set only one of ECC size and ECC strength from DT Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
Re: [PATCH 01/39] mtd: nand: allow to set only one of ECC size and ECC strength from DT Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-11-27 15:00 +0100
[PATCH 06/39] mtd: nand: denali: fix write_oob_data() function Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
[PATCH 03/39] mtd: nand: denali: remove redundant define of BANK(x) Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
[PATCH 05/39] mtd: nand: denali: fix comment of denali_nand_info::flash_mem Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
[PATCH 14/39] mtd: nand: denali: replace uint{8/16/32}_t with u{8/16/32} Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
[PATCH 24/39] mtd: nand: denali: add NEW_N_BANKS_FORMAT capability Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
[PATCH 26/39] mtd: nand: denali: call nand_set_flash_node() to set DT node Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
[PATCH 33/39] mtd: nand: denali: support 1024 byte ECC step size Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
Re: [PATCH 33/39] mtd: nand: denali: support 1024 byte ECC step size Rob Herring <robh@kernel.org> - 2016-12-01 17:00 +0100
[PATCH 10/39] mtd: nand: denali: remove redundant if conditional of erased_check Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
[PATCH 38/39] mtd: nand: denali: remove Toshiba, Hynix specific fixup code Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-26 19:20 +0100
Re: [PATCH 38/39] mtd: nand: denali: remove Toshiba, Hynix specific fixup code Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-11-27 17:30 +0100
Re: [PATCH 00/39] mtd: nand: denali: 2nd round of Denali NAND IP patch bomb Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-11-27 16:10 +0100
Re: [PATCH 00/39] mtd: nand: denali: 2nd round of Denali NAND IP patch bomb Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-30 09:10 +0100
Re: [PATCH 00/39] mtd: nand: denali: 2nd round of Denali NAND IP patch bomb Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-11-30 09:20 +0100
Re: [PATCH 00/39] mtd: nand: denali: 2nd round of Denali NAND IP patch bomb Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-12-01 10:20 +0100
Re: [PATCH 00/39] mtd: nand: denali: 2nd round of Denali NAND IP patch bomb Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-11-30 09:20 +0100
Re: [PATCH 00/39] mtd: nand: denali: 2nd round of Denali NAND IP patch bomb Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-11-27 17:40 +0100
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