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/Documentation/ABI/testing/sysfs-class-mtd b/Documentation/ABI/testing/sysfs-class-mtd
index 7883508..db1ad7e 100644
--- a/Documentation/ABI/testing/sysfs-class-mtd
+++ b/Documentation/ABI/testing/sysfs-class-mtd
@@ -167,7 +167,10 @@
block degradation, but high enough to avoid the consequences of
a persistent return value of -EUCLEAN on devices where sticky
bitflips occur. Note that if bitflip_threshold exceeds
- ecc_strength, -EUCLEAN is never returned by the read functions.
+ ecc_strength, -EUCLEAN is never returned by mtd_read().
+ Conversely, if bitflip_threshold is zero, -EUCLEAN is always
+ returned, absent a hard error.
This is generally applicable only to NAND flash devices with ECC
- capability. It is ignored on devices lacking ECC capability.
+ capability. It is ignored on devices lacking ECC capability;
+ i.e., devices for which ecc_strength is zero.
diff --git a/drivers/mtd/devices/docg3.c b/drivers/mtd/devices/docg3.c
index 8272c02..65d22a0 100644
--- a/drivers/mtd/devices/docg3.c
+++ b/drivers/mtd/devices/docg3.c
@@ -850,6 +850,7 @@
u8 *buf = ops->datbuf;
size_t len, ooblen, nbdata, nboob;
u8 hwecc[DOC_ECC_BCH_SIZE], eccconf1;
+ int max_bitflips = 0;
if (buf)
len = ops->len;
@@ -876,7 +877,7 @@
ret = 0;
skip = from % DOC_LAYOUT_PAGE_SIZE;
mutex_lock(&docg3->cascade->lock);
- while (!ret && (len > 0 || ooblen > 0)) {
+ while (ret >= 0 && (len > 0 || ooblen > 0)) {
calc_block_sector(from - skip, &block0, &block1, &page, &ofs,
docg3->reliable);
nbdata = min_t(size_t, len, DOC_LAYOUT_PAGE_SIZE - skip);
@@ -936,7 +937,8 @@
}
if (ret > 0) {
mtd->ecc_stats.corrected += ret;
- ret = -EUCLEAN;
+ max_bitflips = max(max_bitflips, ret);
+ ret = max_bitflips;
}
}
diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 6a7cba1..5757307 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -800,12 +800,24 @@
int mtd_read(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen,
u_char *buf)
{
+ int ret_code;
*retlen = 0;
if (from < 0 || from > mtd->size || len > mtd->size - from)
return -EINVAL;
if (!len)
return 0;
- return mtd->_read(mtd, from, len, retlen, buf);
+
+ /*
+ * In the absence of an error, drivers return a non-negative integer
+ * representing the maximum number of bitflips that were corrected on
+ * any one ecc region (if applicable; zero otherwise).
+ */
+ ret_code = mtd->_read(mtd, from, len, retlen, buf);
+ if (unlikely(ret_code < 0))
+ return ret_code;
+ if (mtd->ecc_strength == 0)
+ return 0; /* device lacks ecc */
+ return ret_code >= mtd->bitflip_threshold ? -EUCLEAN : 0;
}
EXPORT_SYMBOL_GPL(mtd_read);
diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index ec75d44..d518e4d 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -67,12 +67,12 @@
stats = part->master->ecc_stats;
res = part->master->_read(part->master, from + part->offset, len,
retlen, buf);
- if (unlikely(res)) {
- if (mtd_is_bitflip(res))
- mtd->ecc_stats.corrected += part->master->ecc_stats.corrected - stats.corrected;
- if (mtd_is_eccerr(res))
- mtd->ecc_stats.failed += part->master->ecc_stats.failed - stats.failed;
- }
+ if (unlikely(mtd_is_eccerr(res)))
+ mtd->ecc_stats.failed +=
+ part->master->ecc_stats.failed - stats.failed;
+ else
+ mtd->ecc_stats.corrected +=
+ part->master->ecc_stats.corrected - stats.corrected;
return res;
}
diff --git a/drivers/mtd/nand/alauda.c b/drivers/mtd/nand/alauda.c
index 4f20e1d..60a0dfd 100644
--- a/drivers/mtd/nand/alauda.c
+++ b/drivers/mtd/nand/alauda.c
@@ -414,7 +414,7 @@
}
err = 0;
if (corrected)
- err = -EUCLEAN;
+ err = 1; /* return max_bitflips per ecc step */
if (uncorrected)
err = -EBADMSG;
out:
@@ -446,7 +446,7 @@
}
err = 0;
if (corrected)
- err = -EUCLEAN;
+ err = 1; /* return max_bitflips per ecc step */
if (uncorrected)
err = -EBADMSG;
return err;
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;
}
/**
diff --git a/drivers/mtd/onenand/onenand_base.c b/drivers/mtd/onenand/onenand_base.c
index b3ce12e..7153e0d2 100644
--- a/drivers/mtd/onenand/onenand_base.c
+++ b/drivers/mtd/onenand/onenand_base.c
@@ -1201,7 +1201,8 @@
if (mtd->ecc_stats.failed - stats.failed)
return -EBADMSG;
- return mtd->ecc_stats.corrected - stats.corrected ? -EUCLEAN : 0;
+ /* return max bitflips per ecc step; ONENANDs correct 1 bit only */
+ return mtd->ecc_stats.corrected != stats.corrected ? 1 : 0;
}
/**
@@ -1333,7 +1334,8 @@
if (mtd->ecc_stats.failed - stats.failed)
return -EBADMSG;
- return mtd->ecc_stats.corrected - stats.corrected ? -EUCLEAN : 0;
+ /* return max bitflips per ecc step; ONENANDs correct 1 bit only */
+ return mtd->ecc_stats.corrected != stats.corrected ? 1 : 0;
}
/**
diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index 1482340..2829e8b 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -459,6 +459,8 @@
* @pagemask: [INTERN] page number mask = number of (pages / chip) - 1
* @pagebuf: [INTERN] holds the pagenumber which is currently in
* data_buf.
+ * @pagebuf_bitflips: [INTERN] holds the bitflip count for the page which is
+ * currently in data_buf.
* @subpagesize: [INTERN] holds the subpagesize
* @onfi_version: [INTERN] holds the chip ONFI version (BCD encoded),
* non 0 if ONFI supported.
@@ -519,6 +521,7 @@
uint64_t chipsize;
int pagemask;
int pagebuf;
+ unsigned int pagebuf_bitflips;
int subpagesize;
uint8_t cellinfo;
int badblockpos;