In case OOB write is requested during a data write, ECC is currently lost. Avoid this issue by only writing in the free spare area. This issue has been seen with a YAFFS2 file system.

Signed-off-by: Christophe Kerello christophe.kerello@foss.st.com Cc: stable@vger.kernel.org Fixes: 2cd457f328c1 ("mtd: rawnand: stm32_fmc2: add STM32 FMC2 NAND flash controller driver") --- drivers/mtd/nand/raw/stm32_fmc2_nand.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/nand/raw/stm32_fmc2_nand.c b/drivers/mtd/nand/raw/stm32_fmc2_nand.c index a960403081f11091837b73b8610231fe421d0c05..f84f23392fa441327bec90ba12a2a57d825d9330 100644 --- a/drivers/mtd/nand/raw/stm32_fmc2_nand.c +++ b/drivers/mtd/nand/raw/stm32_fmc2_nand.c @@ -996,9 +996,21 @@ static int stm32_fmc2_nfc_seq_write(struct nand_chip *chip, const u8 *buf,

/* Write oob */ if (oob_required) { - ret = nand_change_write_column_op(chip, mtd->writesize, - chip->oob_poi, mtd->oobsize, - false); + unsigned int offset_in_page = mtd->writesize; + const void *buf = chip->oob_poi; + unsigned int len = mtd->oobsize; + + if (!raw) { + struct mtd_oob_region oob_free; + + mtd_ooblayout_free(mtd, 0, &oob_free); + offset_in_page += oob_free.offset; + buf += oob_free.offset; + len = oob_free.length; + } + + ret = nand_change_write_column_op(chip, offset_in_page, + buf, len, false); if (ret) return ret; }

--- base-commit: fb2fae70e7e985c4acb1ad96110d8b98bb64a87c change-id: 20250811-fix-ecc-overwrite-9962b7797746

Best regards,