UBI: improve Kconfig documentation

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/drivers/mtd/ubi/Kconfig b/drivers/mtd/ubi/Kconfig
index b9daf159a4a7..3f063108e95f 100644
--- a/drivers/mtd/ubi/Kconfig
+++ b/drivers/mtd/ubi/Kconfig
@@ -24,8 +24,13 @@ config MTD_UBI_WL_THRESHOLD
           erase counter value and the lowest erase counter value of eraseblocks
           of UBI devices. When this threshold is exceeded, UBI starts performing
           wear leveling by means of moving data from eraseblock with low erase
-          counter to eraseblocks with high erase counter. Leave the default
-          value if unsure.
+          counter to eraseblocks with high erase counter.
+
+          The default value should be OK for SLC NAND flashes, NOR flashes and
+          other flashes which have eraseblock life-cycle 100000 or more.
+          However, in case of MLC NAND flashes which typically have eraseblock
+          life-cycle less then 10000, the threshold should be lessened (e.g.,
+          to 128 or 256, although it does not have to be power of 2).
 
 config MTD_UBI_BEB_RESERVE
         int "Percentage of reserved eraseblocks for bad eraseblocks handling"