mtd: driver _read() returns max_bitflips; mtd_read() returns -EUCLEAN
The drivers' _read() method, absent an error, returns a non-negative integer
indicating the maximum number of bit errors that were corrected in any one
region comprising an ecc step. MTD returns -EUCLEAN if this is >=
bitflip_threshold, 0 otherwise. If bitflip_threshold is zero, the comparison is
not made since these devices lack ECC and always return zero in the non-error
case (thanks Brian)¹. Note that this is a subtle change to the driver
interface.
This and the preceding patches in this set were tested with ubi on top of the
nandsim and docg4 devices, running the ubi test io_basic from mtd-utils.
¹ http://lists.infradead.org/pipermail/linux-mtd/2012-March/040468.html
Signed-off-by: Mike Dunn <mikedunn@newsguy.com>
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Acked-by: Brian Norris <computersforpeace@gmail.com>
Ivan Djelic <ivan.djelic@parrot.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 9f5d339..640f1f8 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -1486,6 +1486,7 @@
mtd->oobavail : mtd->oobsize;
uint8_t *bufpoi, *oob, *buf;
+ unsigned int max_bitflips = 0;
stats = mtd->ecc_stats;
@@ -1513,7 +1514,10 @@
sndcmd = 0;
}
- /* Now read the page into the buffer */
+ /*
+ * Now read the page into the buffer. Absent an error,
+ * the read methods return max bitflips per ecc step.
+ */
if (unlikely(ops->mode == MTD_OPS_RAW))
ret = chip->ecc.read_page_raw(mtd, chip,
bufpoi, page);
@@ -1530,15 +1534,19 @@
break;
}
+ max_bitflips = max_t(unsigned int, max_bitflips, ret);
+
/* Transfer not aligned data */
if (!aligned) {
if (!NAND_SUBPAGE_READ(chip) && !oob &&
!(mtd->ecc_stats.failed - stats.failed) &&
- (ops->mode != MTD_OPS_RAW))
+ (ops->mode != MTD_OPS_RAW)) {
chip->pagebuf = realpage;
- else
+ chip->pagebuf_bitflips = ret;
+ } else {
/* Invalidate page cache */
chip->pagebuf = -1;
+ }
memcpy(buf, chip->buffers->databuf + col, bytes);
}
@@ -1571,6 +1579,8 @@
} else {
memcpy(buf, chip->buffers->databuf + col, bytes);
buf += bytes;
+ max_bitflips = max_t(unsigned int, max_bitflips,
+ chip->pagebuf_bitflips);
}
readlen -= bytes;
@@ -1609,7 +1619,7 @@
if (mtd->ecc_stats.failed - stats.failed)
return -EBADMSG;
- return mtd->ecc_stats.corrected - stats.corrected ? -EUCLEAN : 0;
+ return max_bitflips;
}
/**