mtd: bitflip_threshold added to mtd_info and sysfs

An element 'bitflip_threshold' is added to struct mtd_info, and also exposed as
a read/write variable in sysfs.  This will be used to determine whether or not
mtd_read() returns -EUCLEAN or 0 (absent a hard error).  If the driver leaves it
as zero, mtd will set it to a default value of ecc_strength.

This v2 adds the line that propagates bitflip_threshold from the master to the
partitions - thanks Ivan¹.

¹ http://lists.infradead.org/pipermail/linux-mtd/2012-April/040900.html

Signed-off-by: Mike Dunn <mikedunn@newsguy.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index cd0119d19cd9..63dadc0dfb62 100644
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -157,6 +157,15 @@ struct mtd_info {
         unsigned int erasesize_mask;
         unsigned int writesize_mask;
 
+        /*
+         * read ops return -EUCLEAN if max number of bitflips corrected on any
+         * one region comprising an ecc step equals or exceeds this value.
+         * Settable by driver, else defaults to ecc_strength.  User can override
+         * in sysfs.  N.B. The meaning of the -EUCLEAN return code has changed;
+         * see Documentation/ABI/testing/sysfs-class-mtd for more detail.
+         */
+        unsigned int bitflip_threshold;
+
         // Kernel-only stuff starts here.
         const char *name;
         int index;