Hi Gary,
I think I have found something that could explain this behaviour. They
happen to be on u-boot side. In fact I just wrote to u-boot mailin list
about this. I'll copy it below:
Linux 3.8.13 seems to use 52 ecc bytes mapping them to positions 12..64.
Default u-boot set-up found from include/asm/arch-am33x/omap_
gpmc.h define:
#define GPMC_NAND_HW_BCH8_ECC_LAYOUT {\
.eccbytes = 56,\
.eccpos = {2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,\
16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,\
28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39,\
40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,\
52, 53, 54, 55, 56, 57},\
.oobfree = {\
{.offset = 58,\
.length = 6 } } \
}
that seems using 56 ecc bytes, mapping them to positions 2..57.
This 56 bytes seems fighting with the fact found from u-boot
README.omap3/BCH8 set-up that points, that
* CONFIG_SYS_NAND_ECCBYTES must be 13 for this BCH8 set-up
On the other hand, am335x_evm.h use CONFIG_SYS_NAND_ECCBYTES to calculate
CONFIG_SYS_NAND_ECCTOTAL that is same as .eccbytes in
GPMC_NAND_HW_BCH8_ECC_LAYOUT definition. Value 13 gives 52 bytes that is
compatible with Linux whereas 14 gives that 56 found from
GPMC_NAND_HW_BCH8_ECC_LAYOUT definition above.
Also text in README.omap3 states:
"The NAND OOB layout is the same as in linux kernel, if the linux kernel
BCH8
implementation for OMAP3 works for you so the u-boot version should also.
When you require the SPL to read with BCH8 there are two more configs to
change:
* CONFIG_SYS_NAND_ECCPOS (must be the same as .eccpos in
GPMC_NAND_HW_BCH8_ECC_LAYOUT defined in
arch/arm/include/asm/arch-
omap3/omap_gpmc.h)
* CONFIG_SYS_NAND_ECCSIZE must be 512
* CONFIG_SYS_NAND_ECCBYTES must be 13 for this BCH8 setup"
I would interpret this so that no modifications are needed
GPMC_NAND_HW_BCH8_ECC_LAYOUT structure.
That can't be true even if the mapping was the same as .eccbytes field have
wrong value considering what the last line states for BCH8 set-up.
If above assumption is correct, isn't this really a bug in omap_gpmc.h, not
just a Linux version related problem?
Regards,
Matti
2013/10/25 Gary Thomas <g...@mlbassoc.com>
> On 2013-10-25 00:01, matti kaasinen wrote:
>
>> Hi!
>>
>> Do anyone happen to know how u-boot should be set to access Linux created
>> ubifs partition correctly? I'm working on beaglebone variant board with
>> nand flash addition. Linux side (3.8.13) seems working fine provided that
>> I
>> don't mount it in u-boot side. However, if i do, it gets corrupted. For
>> instance, if I attach Linux created ubifs partition (ubi part
>> <partition>),
>> i will get tons of "ECC: uncorrectable" errors. After re-boot also Linux
>> side will get these errors.
>>
>> I'm using Angstrom distribution with following details.
>> BB_VERSION = "1.17.0"
>> TARGET_ARCH = "arm"
>> TARGET_OS = "linux-gnueabi"
>> MACHINE = "beaglebone"
>> DISTRO = "angstrom"
>> DISTRO_VERSION = "v2012.12"
>> TUNE_FEATURES = "armv7a vfp neon cortexa8"
>> TARGET_FPU = "vfp-neon"
>>
>> Any hints warmly appreciated.
>>
>
> Details about your NAND device will probably be necessary as well as the
> actual errors and operations you tried.
>
> I suspect that the problem may have to do with NAND sub-page writes. I've
> experienced this on other platforms and was able to work around it by not
> letting UBI use them. For example on my 2K Micron NAND device, I use this
> command to attach:
> # ubiattach /dev/ubi_ctrl -m 3 -O 2048
> The -O option forces the UBI system to only use 2048 byte writes, as
> opposed
> to the 512 byte sub-pages that it would like to use.
>
> If you want to boot with this as your file system, use these kernel command
> line options:
> root=ubi0:root ubi.mtd=3,2048 rootfstype=ubifs
>
> See if this helps. If not, send as many details as you can.
>
> --
> ------------------------------**------------------------------
> Gary Thomas | Consulting for the
> MLB Associates | Embedded world
> ------------------------------**------------------------------
>
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