Re: [i.MX28 GPMI] problem overwriting all-0xff data in NAND

Lothar Waßmann
2011-07-20T06:22:21Z

Hi,

Huang Shijie writes:
> Hi,
> > Hi,
> >
> > Huang Shijie writes:
> >> 于 2011年07月19日 14:02, Lothar Waßmann 写道:
> >>> Hi,
> >>>
> >>> Huang Shijie writes:
> >>>> hi Lothar:
> >>>>> On Mon, Jul 18, 2011 at 03:13:27PM +0200, Lothar Waßmann wrote:
> >>>>>> Hi,
> >>>>>>
> >>>>>> with the gpmi-nfc driver for imx28 from Shawn Guo on a TX28 I
> >>>>> To be clear, the author of gpmi-nfc driver is Huang Shijie (Cc-ed).
> >>>>>
> >>>>> Regards,
> >>>>> Shawn
> >>>>>
> >>>>>> encountered some problems with jffs2 when overwriting pages that have
> >>>>>> been written with 0xff (e.g. from padding from the file system image
> >>>>>> file).
> >>>> The GPMI driver now does not support the JFFS2 very well.
> >>>> The JFFS2 will write the OOB, while the BCH of GPMI will use the OOB too.
> >>>>
> >>> I have applied a patch (from the Freescale BSPs) that prevents JFFS2
> >>> from using the OOB area. But this still doesn't help.
> >>>
> >> Could you show the log ?
> >>
> > On the host:
> > mkfs.jffs2 -o ../rootfs.img -n -e 0x20000 -p -r .
> > The last block gets padded with a stretch of 91840 bytes of 0xff.
> > On the target:
> > flash_eraseall /dev/mtd2
> > nandwrite /dev/mtd2 /rootfs-jffs2.image
> > The raw data of the last used block in flash looks like this
> > afterwards:
> > nanddump -n -p -l 0x800 -s 0x889800 /dev/mtd2
> > |Block size 131072, page size 2048, OOB size 64
> > |Dumping data starting at 0x00889800 and ending at 0x0088a000...
> > |0x00889800: ff ff ff ff ff ff ff ff ff ff b7 00 00 00 f2 00
> > |0x00889810: 00 00 06 00 00 00 7f ca a1 e3 e4 1f e9 24 78 5e
> > |0x00889820: 34 8f 41 0e 83 30 0c 04 ef 7d 85 25 ae 6d f3 8e
> > |0x00889830: de fb 81 10 0c b1 08 76 e4 18 10 bf af 83 d4 93
> > |0x00889840: 2d 6b 67 77 3d c0 37 53 83 99 0a 82 cf 76 6d 85
> > |0x00889850: 78 c5 09 4c 20 a0 a5 a0 d8 a4 1c ef 24 3c 3f 06
> > |0x00889860: f8 58 57 ad 58 7d 32 84 23 6a d0 9d c3 94 53 4d
> > |0x00889870: a1 33 23 42 1c dd cb d7 4d 76 36 b0 8c a0 22 36
> > |0x00889880: 37 c7 15 e3 f4 12 2e 17 9c b9 27 56 77 47 3d 88
> > |0x00889890: 97 5b 57 a5 35 1a a9 90 5d dd 20 c7 c3 4b 99 53
> > |0x008898a0: a7 92 19 b2 3b 8c 17 dc 61 d3 13 68 be 21 46 3b
> > |0x008898b0: 45 57 e8 0d 69 d9 35 1a 09 f7 96 ff 83 3f f3 13
> > |0x008898c0: 40 69 f9 45 0a 2e 1e ce 01 7a 5c ca 5c 00 01 06
> > |0x008898d0: 00 2b 56 54 c6 ff 85 19 01 e0 2f 00 00 00 b1 f9
> > |0x008898e0: 44 f2 c2 03 00 00 d5 03 00 00 c8 03 00 00 a7 ac
> > |0x008898f0: e3 4d 07 08 00 00 55 81 af 84 e8 5f 94 39 79 70
> > |0x00889900: 2e 63 6f 6e 66 ff 85 19 02 e0 44 00 00 00 1d fb
> > |0x00889910: f7 98 c8 03 00 00 01 00 00 00 a4 81 00 00 00 00
> > |0x00889920: 00 00 00 00 00 00 a7 ac e3 4d a7 ac e3 4d a7 ac
> > |0x00889930: e3 4d 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> > |0x00889940: 00 00 00 00 00 00 13 77 d1 ba ff ff ff ff ff ff
> > |0x00889950: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> > [...]
> > |0x00889a00: ff ff ff ff ff ff ff ff ff ff 27 21 37 1b 06 87
> > |0x00889a10: 70 f1 00 0e 6a 8e 57 ff ff ff ff ff ff ff ff ff
> > |0x00889a20: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> > [...]
> > |0x00889c10: ff ff ff ff ff ff ff 08 75 8b 6f 48 36 a6 bc 16
> > |0x00889c20: 61 58 db 52 ff ff ff ff ff ff ff ff ff ff ff ff
> > |0x00889c30: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> > [...]
> > |0x00889e20: ff ff ff ff 08 75 8b 6f 48 36 a6 bc 16 61 58 db
> > |0x00889e30: 52 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> > |0x00889e40: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> > [...]
> > | OOB Data: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> > | OOB Data: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> > | OOB Data: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> > | OOB Data: ff 08 75 8b 6f 48 36 a6 bc 16 61 58 db 52 00 00
> >
> > The remaining pages of this block are all-FF except for the ecc
> > pattern as above.
> >
> > Checking the readability of the whole flash partition shows no errors:
> > dd if=/dev/mtdblock2 of=/dev/null
> > |32768+0 records in
> > |32768+0 records out
> > |16777216 bytes (17 MB) copied, 18.6754 s, 898 kB/s
> >
> > Mounting the partition and writing some file produces ecc errors upon
> > successive reads:
> > mount -t jffs2 /dev/mtdblock2 /mnt
> > touch /mnt/xxx
> It seems the writing of JFFS2 corrupted something.
> So the following commands will fail.
>
It doesn't only seem so.
JFFS2 overwrites the all-FF page without erasing the block containing
that page, but since the ECC pattern for an all-FF page is NOT all-FF
the ECC information cannot be written correctly and ECC errors occur
on a subsequent read.

Lothar Waßmann
--
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