diff options
| author | Mike Dunn <mikedunn@newsguy.com> | 2012-04-25 12:06:11 -0700 |
|---|---|---|
| committer | David Woodhouse <David.Woodhouse@intel.com> | 2012-05-13 23:14:23 -0500 |
| commit | edbc4540e02c201bdd4f4d498ebb6ed517fd36e2 (patch) | |
| tree | 403ee7318cb1218a224885d048781e35f2128a22 /Documentation | |
| parent | e2788c98b98269a3131bffd2b57599280d7abd73 (diff) | |
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 'Documentation')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-class-mtd | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/Documentation/ABI/testing/sysfs-class-mtd b/Documentation/ABI/testing/sysfs-class-mtd index 78835080856..db1ad7e34fc 100644 --- a/Documentation/ABI/testing/sysfs-class-mtd +++ b/Documentation/ABI/testing/sysfs-class-mtd @@ -167,7 +167,10 @@ Description: 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. |