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mtd: nand: gpmi: Fix failure when a erased page has a bitflip at BBM

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When erased subpages are read then the BCH decoder returns STATUS_ERASED
if they are all empty, or STATUS_UNCORRECTABLE if there are bitflips.
When there are bitflips, we have to set these bits again to show the
upper layers a completely erased page. When a bitflip happens in the
exact byte where the bad block marker is, then this byte is swapped
with another byte in block_mark_swapping(). The correction code then
detects a bitflip in another subpage and no longer corrects the bitflip
where it really happens.

Correct this behaviour by calling block_mark_swapping() after the
bitflips have been corrected.

In our case UBIFS failed with this bug because it expects erased
pages to be really empty:

UBIFS error (pid 187): ubifs_scan: corrupt empty space at LEB 36:118735
UBIFS error (pid 187): ubifs_scanned_corruption: corruption at LEB 36:118735
UBIFS error (pid 187): ubifs_scanned_corruption: first 8192 bytes from LEB 36:118735
UBIFS error (pid 187): ubifs_scan: LEB 36 scanning failed
UBIFS error (pid 187): do_commit: commit failed, error -117

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Richard Weinberger <richard@nod.at>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Sascha Hauer 2017-12-05 11:51:40 +01:00 committed by Richard Weinberger
parent 50c4c4e268
commit fdf2e82105
1 changed files with 3 additions and 3 deletions
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6
drivers/mtd/nand/gpmi-nand/gpmi-nand.c
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@ -1067,9 +1067,6 @@ static int gpmi_ecc_read_page(struct mtd_info *mtd, struct nand_chip *chip,
return ret;
}
/* handle the block mark swapping */
block_mark_swapping(this, payload_virt, auxiliary_virt);
/* Loop over status bytes, accumulating ECC status. */
status = auxiliary_virt + nfc_geo->auxiliary_status_offset;
@ -1158,6 +1155,9 @@ static int gpmi_ecc_read_page(struct mtd_info *mtd, struct nand_chip *chip,
max_bitflips = max_t(unsigned int, max_bitflips, *status);
}
/* handle the block mark swapping */
block_mark_swapping(this, buf, auxiliary_virt);
if (oob_required) {
/*
* It's time to deliver the OOB bytes. See gpmi_ecc_read_oob()