UBI: improve Kconfig documentation

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=6e0c84e37e809e79313043385148020ceb760496
Commit:     6e0c84e37e809e79313043385148020ceb760496
Parent:     c4506092c1773211b71a75bd557c02b090c82b66
Author:     Artem Bityutskiy <Artem.Bityutskiy at nokia.com>
AuthorDate: Thu Mar 27 17:18:45 2008 +0200
Committer:  Artem Bityutskiy <Artem.Bityutskiy at nokia.com>
CommitDate: Thu Apr 17 11:32:00 2008 +0300

    UBI: improve Kconfig documentation
    
    Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy at nokia.com>
---
 drivers/mtd/ubi/Kconfig |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/ubi/Kconfig b/drivers/mtd/ubi/Kconfig
index b9daf15..3f06310 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"