From: Boris Brezillon <boris.brezillon@free-electrons.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: richard@nod.at, mark.marshall@omicronenergy.com,
linux-kernel@vger.kernel.org, marek.vasut@gmail.com,
linux-mtd@lists.infradead.org, Dipen.Dudhat@freescale.com,
cyrille.pitchen@atmel.com, computersforpeace@gmail.com,
dwmw2@infradead.org, prabhakar@freescale.com,
b44839@freescale.com
Subject: Re: tango_nand: is logic right in error cases? (was Re: fsl_ifc_nand: are blank pages protected by ECC?)
Date: Mon, 24 Apr 2017 09:12:59 +0200 [thread overview]
Message-ID: <20170424091259.3f091129@bbrezillon> (raw)
In-Reply-To: <20170423095845.GA8692@amd>
On Sun, 23 Apr 2017 11:58:45 +0200
Pavel Machek <pavel@ucw.cz> wrote:
> Hi!
>
> > > Maybe I figured it out. Unfortunately, it is only compile tested. Does
> > > it look approximately right?
> >
> > Yep that's definitely better. Just one thing missing (see below),
> > otherwise it looks good.
>
> I'm copying from tango_nand, therefore I had to check tango_nand, too.
>
> static int check_erased_page(struct nand_chip *chip, u8 *buf)
> {
> ...
> res = nand_check_erased_ecc_chunk(buf, pkt_size, ecc, ecc_size,
> meta, meta_len,
> chip->ecc.strength);
> if (res < 0)
> mtd->ecc_stats.failed++;
> else
> mtd->ecc_stats.corrected += res;
>
> bitflips = max(res, bitflips);
> ...
> return bitflips;
> }
>
> static int tango_read_page(struct mtd_info *mtd, struct nand_chip *chip,
> u8 *buf, int oob_required, int page)
> {
> ...
> res = decode_error_report(nfc);
> if (res < 0) {
> chip->ecc.read_oob_raw(mtd, chip, page);
> res = check_erased_page(chip, buf);
> }
>
> return res;
> }
>
>
> So nand_check_erased_ecc_chunk() returns < 0 (failed ECC), but then we
> perform max() with bitflips (lets say 1, correctable ECC) and return
> 1? tango_read_page then returns 1 (correctable ECC) forgetting about
> failed ECC...?
Yep, that's expected, see what's done in the core to detect
uncorrectable errors and return EBADMSG when appropriate [1].
[1]http://lxr.free-electrons.com/source/drivers/mtd/nand/nand_base.c#L2033
prev parent reply other threads:[~2017-04-24 7:13 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-19 12:13 fsl_ifc_nand: are blank pages protected by ECC? Pavel Machek
2017-04-19 21:18 ` Boris Brezillon
2017-04-19 22:15 ` Pavel Machek
2017-04-19 22:27 ` Boris Brezillon
2017-04-20 11:40 ` Pavel Machek
2017-04-20 12:15 ` Boris Brezillon
2017-04-21 10:51 ` [PATCH] nand_base: optimize checking of erased buffers Pavel Machek
2017-05-17 11:27 ` Mason
2017-05-17 11:39 ` Mason
2017-05-17 11:52 ` Pavel Machek
2017-05-17 12:22 ` [PATCH] fsl_ifc_nand: fix handing of bit flips in erased nand Pavel Machek
2017-05-17 12:32 ` Boris Brezillon
2017-05-17 13:00 ` Pavel Machek
2017-05-17 13:25 ` Boris Brezillon
2017-05-17 20:03 ` [PATCH] mtd: nand: fsl_ifc: fix handing of bit flips in erased pages Pavel Machek
2017-05-31 20:59 ` [PATCHv2] " Pavel Machek
2017-05-31 22:59 ` Darwin Dingel
2017-06-01 1:09 ` Darwin Dingel
2017-06-01 13:12 ` Pavel Machek
2017-06-01 13:21 ` Boris Brezillon
2017-06-07 7:31 ` Boris Brezillon
2017-04-21 10:08 ` fsl_ifc_nand: are blank pages protected by ECC? Pavel Machek
2017-04-21 10:12 ` Richard Weinberger
2017-04-21 12:04 ` Boris Brezillon
2017-04-21 13:37 ` Pavel Machek
2017-04-21 13:49 ` Boris Brezillon
2017-04-22 7:01 ` Pavel Machek
2017-04-22 10:40 ` [PATCH] tango_nand.c: fix ecc.stats_corrected in empty flash case Pavel Machek
2017-04-23 9:58 ` tango_nand: is logic right in error cases? (was Re: fsl_ifc_nand: are blank pages protected by ECC?) Pavel Machek
2017-04-24 7:12 ` Boris Brezillon [this message]
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