diff options
Diffstat (limited to 'Documentation/ABI/testing/sysfs-class-mtd')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-class-mtd | 42 |
1 files changed, 26 insertions, 16 deletions
diff --git a/Documentation/ABI/testing/sysfs-class-mtd b/Documentation/ABI/testing/sysfs-class-mtd index db1ad7e34fc..1399bb2da3e 100644 --- a/Documentation/ABI/testing/sysfs-class-mtd +++ b/Documentation/ABI/testing/sysfs-class-mtd @@ -14,8 +14,7 @@ Description: The /sys/class/mtd/mtd{0,1,2,3,...} directories correspond to each /dev/mtdX character device. These may represent physical/simulated flash devices, partitions on a flash - device, or concatenated flash devices. They exist regardless - of whether CONFIG_MTD_CHAR is actually enabled. + device, or concatenated flash devices. What: /sys/class/mtd/mtdXro/ Date: April 2009 @@ -23,8 +22,7 @@ KernelVersion: 2.6.29 Contact: linux-mtd@lists.infradead.org Description: These directories provide the corresponding read-only device - nodes for /sys/class/mtd/mtdX/ . They are only created - (for the benefit of udev) if CONFIG_MTD_CHAR is enabled. + nodes for /sys/class/mtd/mtdX/ . What: /sys/class/mtd/mtdX/dev Date: April 2009 @@ -106,7 +104,7 @@ Description: One of the following ASCII strings, representing the device type: - absent, ram, rom, nor, nand, dataflash, ubi, unknown + absent, ram, rom, nor, nand, mlc-nand, dataflash, ubi, unknown What: /sys/class/mtd/mtdX/writesize Date: April 2009 @@ -130,9 +128,8 @@ KernelVersion: 3.4 Contact: linux-mtd@lists.infradead.org Description: Maximum number of bit errors that the device is capable of - correcting within each region covering an ecc step. This will - always be a non-negative integer. Note that some devices will - have multiple ecc steps within each writesize region. + correcting within each region covering an ECC step (see + ecc_step_size). This will always be a non-negative integer. In the case of devices lacking any ECC capability, it is 0. @@ -142,13 +139,14 @@ KernelVersion: 3.4 Contact: linux-mtd@lists.infradead.org Description: This allows the user to examine and adjust the criteria by which - mtd returns -EUCLEAN from mtd_read(). If the maximum number of - bit errors that were corrected on any single region comprising - an ecc step (as reported by the driver) equals or exceeds this - value, -EUCLEAN is returned. Otherwise, absent an error, 0 is - returned. Higher layers (e.g., UBI) use this return code as an - indication that an erase block may be degrading and should be - scrutinized as a candidate for being marked as bad. + mtd returns -EUCLEAN from mtd_read() and mtd_read_oob(). If the + maximum number of bit errors that were corrected on any single + region comprising an ecc step (as reported by the driver) equals + or exceeds this value, -EUCLEAN is returned. Otherwise, absent + an error, 0 is returned. Higher layers (e.g., UBI) use this + return code as an indication that an erase block may be + degrading and should be scrutinized as a candidate for being + marked as bad. The initial value may be specified by the flash device driver. If not, then the default value is ecc_strength. @@ -167,10 +165,22 @@ 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 mtd_read(). + ecc_strength, -EUCLEAN is never returned by the read operations. 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; i.e., devices for which ecc_strength is zero. + +What: /sys/class/mtd/mtdX/ecc_step_size +Date: May 2013 +KernelVersion: 3.10 +Contact: linux-mtd@lists.infradead.org +Description: + The size of a single region covered by ECC, known as the ECC + step. Devices may have several equally sized ECC steps within + each writesize region. + + It will always be a non-negative integer. In the case of + devices lacking any ECC capability, it is 0. |