From: Boris Brezillon <boris.brezillon@free-electrons.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: richard@nod.at, dwmw2@infradead.org, computersforpeace@gmail.com,
marek.vasut@gmail.com, cyrille.pitchen@atmel.com,
linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org,
mark.marshall@omicronenergy.com, b44839@freescale.com,
prabhakar@freescale.com
Subject: Re: fsl_ifc_nand: are blank pages protected by ECC?
Date: Wed, 19 Apr 2017 23:18:04 +0200 [thread overview]
Message-ID: <20170419231804.5a04ed69@bbrezillon> (raw)
In-Reply-To: <20170419121332.GA26979@amd>
On Wed, 19 Apr 2017 14:13:32 +0200
Pavel Machek <pavel@ucw.cz> wrote:
> Hi!
>
> We have some problems with fsl_ifc_nand ... in the old kernels, but
> this one does not seem to be fixed in v4.11, either.
>
> UBIFS complains:
>
> UBIFS error (pid 931): ubifs_scan: corrupt empty space at LEB 282:252630
> UBIFS error (pid 931): ubifs_scanned_corruption: corruption at LEB 282:252630
> UBIFS error (pid 931): ubifs_scanned_corruption: first 1322 bytes from LEB 282:252630
> UBIFS error (pid 931): ubifs_scan: LEB 282 scanning failed
>
> Possible explanation is here:
>
> https://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/t/289605
>
> # I see on the forum that this issue has been raised before - my
> # understanding is that the omap2 nand driver does not perform ECC
> # detection/correction on empty pages so when UBIFS checks the empty
> # space data and doesn't read all 0xFF then it fails and mounts
> # read-only. I didn't find any good solution - only a workaround to
> # remove the UBIFS check..
>
> So I checked fsl_ifc_nand.c in v4.11-rc, and yes, it seems to have the
> same problem:
>
> if (errors == 15) {
> /*
> * Uncorrectable error.
> * OK only if the whole page is blank.
> *
> * We disable ECCER reporting due to...
> * erratum IFC-A002770 -- so report it now if we
> * see an uncorrectable error in ECCSTAT.
> */
> if (!is_blank(mtd, bufnum))
> ctrl->nand_stat |=
> IFC_NAND_EVTER_STAT_ECCER;
> break;
> }
>
> is_blank() checks for all 0xff's, so single-bit 0xfe in the data will
> result in_blank() == 0 and uncorrectable error being signaled.
>
> Should the driver be modified somehow?
Yep, nand_check_erased_ecc_chunk() [1] is here to help you check this
case, unfortunately, it's not directly applicable here, because this
function takes regular pointers and not __iomem ones. You'll either
have to copy the data in an intermediate buffer before calling
nand_check_erased_ecc_chunk(), or cast the SRAM region to a void
pointer (which is usually not a good idea). The last option would be to
open code nand_check_erased_ecc_chunk(), but I'd really like to avoid
that (for maintainability concerns).
[1]http://lxr.free-electrons.com/source/drivers/mtd/nand/nand_base.c#L1414
next prev parent reply other threads:[~2017-04-19 21:18 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 [this message]
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
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