From eb237a15bd793a785feb0c77c459c9f97c6fbe4c Mon Sep 17 00:00:00 2001 From: Nikita Kiryanov Date: Mon, 16 Dec 2013 19:19:01 +0200 Subject: [PATCH] mtd: nand: omap: fix sw->hw->sw ecc switch When switching ecc mode, omap_select_ecc_scheme() assigns the appropriate values into the current nand chip's ecc.layout struct. This is done under the assumption that the struct exists only to store values, so it is OK to overwrite it, but there is at least one situation where this assumption is incorrect: When switching to 1 bit hamming code sw ecc, the job of assigning layout data is outsourced to nand_scan_tail(), which simply assigns into ecc.layout a pointer to an existing struct prefilled with the appropriate values. This struct doubles as both data and layout definition, and therefore shouldn't be overwritten, but on the next switch to hardware ecc, this is exactly what's going to happen. The next time the user switches to software ecc, they're going to get a messed up ecc layout. Prevent this and possible similar bugs by explicitly using the private-to-omap_gpmc.c omap_ecclayout struct when switching ecc mode. Cc: Scott Wood Cc: Pekon Gupta Signed-off-by: Nikita Kiryanov --- drivers/mtd/nand/omap_gpmc.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/mtd/nand/omap_gpmc.c b/drivers/mtd/nand/omap_gpmc.c index d5c4c2269c..3405ed502b 100644 --- a/drivers/mtd/nand/omap_gpmc.c +++ b/drivers/mtd/nand/omap_gpmc.c @@ -763,7 +763,7 @@ static void __maybe_unused omap_free_bch(struct mtd_info *mtd) static int omap_select_ecc_scheme(struct nand_chip *nand, enum omap_ecc ecc_scheme, unsigned int pagesize, unsigned int oobsize) { struct nand_bch_priv *bch = nand->priv; - struct nand_ecclayout *ecclayout = nand->ecc.layout; + struct nand_ecclayout *ecclayout = &omap_ecclayout; int eccsteps = pagesize / SECTOR_BYTES; int i; @@ -897,6 +897,11 @@ static int omap_select_ecc_scheme(struct nand_chip *nand, debug("nand: error: ecc scheme not enabled or supported\n"); return -EINVAL; } + + /* nand_scan_tail() sets ham1 sw ecc; hw ecc layout is set by driver */ + if (ecc_scheme != OMAP_ECC_HAM1_CODE_SW) + nand->ecc.layout = ecclayout; + return 0; } -- 2.39.5