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authorMike Dunn <mikedunn@newsguy.com>2012-04-25 23:06:11 +0400
committerDavid Woodhouse <David.Woodhouse@intel.com>2012-05-14 08:14:23 +0400
commitedbc4540e02c201bdd4f4d498ebb6ed517fd36e2 (patch)
tree403ee7318cb1218a224885d048781e35f2128a22 /drivers/mtd/mtdcore.c
parente2788c98b98269a3131bffd2b57599280d7abd73 (diff)
downloadlinux-edbc4540e02c201bdd4f4d498ebb6ed517fd36e2.tar.xz
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>
Diffstat (limited to 'drivers/mtd/mtdcore.c')
-rw-r--r--drivers/mtd/mtdcore.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 6a7cba1e24e6..575730744fdb 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -800,12 +800,24 @@ EXPORT_SYMBOL_GPL(mtd_get_unmapped_area);
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);