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author | Peng Fan <peng.fan@nxp.com> | 2016-05-06 12:13:38 +0800 |
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committer | Ye Li <ye.li@nxp.com> | 2017-04-05 14:04:27 +0800 |
commit | 026751697e41c7376414a8716cf0ea4bf998b85f (patch) | |
tree | 91acb01c97a1c846f484da9ab0fcfb6684e57eef /.gitignore | |
parent | 58794b3ebefea468bb1c57184b79df500f427927 (diff) | |
download | u-boot-imx-026751697e41c7376414a8716cf0ea4bf998b85f.zip u-boot-imx-026751697e41c7376414a8716cf0ea4bf998b85f.tar.gz u-boot-imx-026751697e41c7376414a8716cf0ea4bf998b85f.tar.bz2 |
MLK-12693-1 nand: mxs: fix the bitflips for erased page when uncorrectable error
This patch is porting from linux:
http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/commit/?h=imx_4.1.15_1.0.0_ga&id=3d42fcece496224fde59f9343763fb2dfc5b0768
"
We may meet the bitflips in reading an erased page(contains all 0xFF),
this may causes the UBIFS corrupt, please see the log from Elie:
-----------------------------------------------------------------
[ 3.831323] UBI warning: ubi_io_read: error -74 (ECC error) while reading 16384 bytes from PEB 443:245760, read only 16384 bytes, retry
[ 3.845026] UBI warning: ubi_io_read: error -74 (ECC error) while reading 16384 bytes from PEB 443:245760, read only 16384 bytes, retry
[ 3.858710] UBI warning: ubi_io_read: error -74 (ECC error) while reading 16384 bytes from PEB 443:245760, read only 16384 bytes, retry
[ 3.872408] UBI error: ubi_io_read: error -74 (ECC error) while reading 16384 bytes from PEB 443:245760, read 16384 bytes
...
[ 4.011529] UBIFS error (pid 36): ubifs_recover_leb: corrupt empty space LEB 27:237568, corruption starts at 9815
[ 4.021897] UBIFS error (pid 36): ubifs_scanned_corruption: corruption at LEB 27:247383
[ 4.030000] UBIFS error (pid 36): ubifs_scanned_corruption: first 6569 bytes from LEB 27:247383
-----------------------------------------------------------------
This patch does a check for the uncorrectable failure in the following steps:
[0] set the threshold.
The threshold is set based on the truth:
"A single 0 bit will lead to gf_len(13 or 14) bits 0 after the BCH
do the ECC."
For the sake of safe, we will set the threshold with half the gf_len, and
do not make it bigger the ECC strength.
[1] count the bitflips of the current ECC chunk, assume it is N.
[2] if the (N <= threshold) is true, we continue to read out the page with
ECC disabled. and we count the bitflips again, assume it is N2.
(We read out the whole page, not just a chunk, this makes the check
more strictly, and make the code more simple.)
[3] if the (N2 <= threshold) is true again, we can regard this is a erased
page. This is because a real erased page is full of 0xFF(maybe also has
several bitflips), while a page contains the 0xFF data will definitely
has many bitflips in the ECC parity areas.
[4] if the [3] fails, we can regard this is a page filled with the '0xFF'
data.
"
Signed-off-by: Peng Fan <peng.fan@nxp.com>
(cherry picked from commit ceb324a2914487aa517a6c70a06a20b5e3438fda)
Diffstat (limited to '.gitignore')
0 files changed, 0 insertions, 0 deletions