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mtd: nand: relax ecc.read_page() return value for uncorrectable ECC

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The comment for ecc.read_page() requires that it should return
"0 if bitflips uncorrectable".

Actually, drivers could return positive values when uncorrectable
bitflips occur.  For example, nand_read_page_swecc() is the case.
If ecc.correct() returns -EBADMSG for the first ECC sector, and
a positive value for the second one, nand_read_page_swecc() returns
a positive max_bitflips and increments ecc_stats.failed for the same
page.

The requirement can be relaxed by tweaking nand_do_read_ops().
Move the max_bitflips calculation below the retry.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Suggested-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
This commit is contained in:
Masahiro Yamada 2017-03-30 15:45:47 +09:00 committed by Boris Brezillon
parent f107d7a439
commit 07604686e8
2 changed files with 2 additions and 3 deletions
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3
drivers/mtd/nand/nand_base.c
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@ -1993,8 +1993,6 @@ read_retry:
break;
}
max_bitflips = max_t(unsigned int, max_bitflips, ret);
/* Transfer not aligned data */
if (use_bufpoi) {
if (!NAND_HAS_SUBPAGE_READ(chip) && !oob &&
@ -2045,6 +2043,7 @@ read_retry:
}
buf += bytes;
max_bitflips = max_t(unsigned int, max_bitflips, ret);
} else {
memcpy(buf, chip->buffers->databuf + col, bytes);
buf += bytes;

2
include/linux/mtd/nand.h
View file

@ -516,7 +516,7 @@ static inline void nand_hw_control_init(struct nand_hw_control *nfc)
* out-of-band data).
* @read_page: function to read a page according to the ECC generator
* requirements; returns maximum number of bitflips corrected in
* any single ECC step, 0 if bitflips uncorrectable, -EIO hw error
* any single ECC step, -EIO hw error
* @read_subpage: function to read parts of the page covered by ECC;
* returns same as read_page()
* @write_subpage: function to write parts of the page covered by ECC.