UBI ECC errors on kernel 3.16.2

[Angelo Dureghello]

Hi all,

still some updated on these -74 EBADMSG i am receiving.

well, seems the first ecc error is detected as soon as the kernel driver 
starts to
read the ubifs (so file system) data part of the rootfs.ubi image.

Before reading the file system data, so attaching, there is no ecc error 
detected at all.
I added traces on some kernel file as nand_base.c.


Ubi scanning / attaching  ...

nand_read_page_hwecc_oob_first page    :3659
nand_read_page_hwecc_oob_first correct p:c883d800 p[0]:p[1] 00:00 i:0 
eccpos[i]:06 ecc_code[i]:0b;
nand_read_page_hwecc_oob_first correct p:c883da00 p[0]:p[1] 00:00 i:10 
eccpos[i]:16 ecc_code[i]:58;
nand_read_page_hwecc_oob_first correct p:c883dc00 p[0]:p[1] 00:00 i:20 
eccpos[i]:26 ecc_code[i]:cf;
nand_read_page_hwecc_oob_first correct p:c883de00 p[0]:p[1] 00:00 i:30 
eccpos[i]:36 ecc_code[i]:8b;
nand_read_page_hwecc_oob_first page    :3660
nand_read_page_hwecc_oob_first correct p:c883e000 p[0]:p[1] 00:00 i:0 
eccpos[i]:06 ecc_code[i]:9b;
nand_read_page_hwecc_oob_first correct p:c883e200 p[0]:p[1] 00:00 i:10 
eccpos[i]:16 ecc_code[i]:f1;
nand_read_page_hwecc_oob_first correct p:c883e400 p[0]:p[1] 00:00 i:20 
eccpos[i]:26 ecc_code[i]:26;
nand_read_page_hwecc_oob_first correct p:c883e600 p[0]:p[1] ff:ff i:30 
eccpos[i]:36 ecc_code[i]:3f;
UBI: volume 0 ("rootfs") re-sized from 205 to 456 LEBs
UBI: attached mtd6 (name "rootfs", size 60 MiB) to ubi0
UBI: PEB size: 131072 bytes (128 KiB), LEB size: 126976 bytes
UBI: min./max. I/O unit sizes: 2048/2048, sub-page size 512
UBI: VID header offset: 2048 (aligned 2048), data offset: 4096
UBI: good PEBs: 480, bad PEBs: 0, corrupted PEBs: 0
UBI: user volume: 1, internal volumes: 1, max. volumes count: 128
UBI: max/mean erase counter: 1/0, WL threshold: 4096, image sequence 
number: 272604537
UBI: available PEBs: 0, total reserved PEBs: 480, PEBs reserved for bad 
PEB handling: 20
UBI: background thread "ubi_bgt0d" started, PID 995
gpio-keys gpio-keys.0: Failed to request GPIO 126, error -517
platform gpio-keys.0: Driver gpio-keys requests probe deferral
omap_rtc da830-rtc: setting system clock to 2014-10-02 15:59:28 UTC 
(1412265568)
ALSA device list:
   No soundcards found.

*** reading the file system here ***

At page 3712 there is the first of the file system blocks
3712        3713           3714         3715
EC HEADER  |  VID HEADER  |  fs data   |   fs data   etc
                            ^
                            ^

nand_read_page_hwecc_oob_first page    :3714
nand_read_page_hwecc_oob_first error   p:c7906000 p[0]:p[1] 31:18 i:0 
eccpos[i]:06 ecc_code[i]:1f;    <<< ERROR
nand_read_page_hwecc_oob_first correct p:c7906200 p[0]:p[1] 00:00 i:10 
eccpos[i]:16 ecc_code[i]:00;
nand_read_page_hwecc_oob_first correct p:c7906400 p[0]:p[1] 00:00 i:20 
eccpos[i]:26 ecc_code[i]:00;
nand_read_page_hwecc_oob_first correct p:c7906600 p[0]:p[1] 00:00 i:30 
eccpos[i]:36 ecc_code[i]:00;
ecc_failed !!
nand_read_page_hwecc_oob_first page    :3715
nand_read_page_hwecc_oob_first correct p:c7906800 p[0]:p[1] 00:00 i:0 
eccpos[i]:06 ecc_code[i]:00;
nand_read_page_hwecc_oob_first correct p:c7906a00 p[0]:p[1] 00:00 i:10 
eccpos[i]:16 ecc_code[i]:00;
nand_read_page_hwecc_oob_first correct p:c7906c00 p[0]:p[1] 00:00 i:20 
eccpos[i]:26 ecc_code[i]:00;
nand_read_page_hwecc_oob_first correct p:c7906e00 p[0]:p[1] 00:00 i:30 
eccpos[i]:36 ecc_code[i]:00;
UBI warning: ubi_io_read: error -74 (ECC error) while reading 4096 bytes 
from PEB 2:4096, read only 4096 bytes, retry


I am tracing the first 2 bytes only of each 512B eccblock.
I verified, first 2 bytes with errors (0x31, 0x18) are sane, as in the 
rootfs.ubi file.

So, i am supposing these errors are caused from a misalignment from 
u-boot and kernel davinci / nand drivers
that calculate the ecc values.

U-Boot 2014.07-03397-gab92542 (Oct 02 2014 - 16:14:43)
Kernel is 3.16.2

What do you think ?

Regards angelo