mtd: support reading OOB without ECC
This fixes issues with `nanddump -n' and the MEMREADOOB[64] ioctls on
hardware that performs error correction when reading only OOB data. A
driver for such hardware needs to know when we're doing a RAW vs. a
normal write, but mtd_do_read_oob does not pass such information to the
lower layers (e.g., NAND). We should pass MTD_OOB_RAW or MTD_OOB_PLACE
based on the MTD file mode.
For now, most drivers can get away with just setting:
chip->ecc.read_oob_raw = chip->ecc.read_oob
This is done by default; but for systems that behave as described above,
you must supply your own replacement function.
This was tested with nandsim as well as on actual SLC NAND.
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Cc: Jim Quinlan <jim2101024@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@intel.com>
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index b61a7c7..ad40607 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -1787,7 +1787,10 @@
page = realpage & chip->pagemask;
while (1) {
- sndcmd = chip->ecc.read_oob(mtd, chip, page, sndcmd);
+ if (ops->mode == MTD_OOB_RAW)
+ sndcmd = chip->ecc.read_oob_raw(mtd, chip, page, sndcmd);
+ else
+ sndcmd = chip->ecc.read_oob(mtd, chip, page, sndcmd);
len = min(len, readlen);
buf = nand_transfer_oob(chip, buf, ops, len);
@@ -3385,6 +3388,8 @@
}
/* For many systems, the standard OOB write also works for raw */
+ if (!chip->ecc.read_oob_raw)
+ chip->ecc.read_oob_raw = chip->ecc.read_oob;
if (!chip->ecc.write_oob_raw)
chip->ecc.write_oob_raw = chip->ecc.write_oob;