Merge tag 'upstream-3.7-rc1' of git://git.infradead.org/linux-ubi

Pull UBI changes from Artem Bityutskiy:
 "The main change is the way we reserve eraseblocks for bad blocks
  handling.  We used to reserve 2% of the partition, but now we are more
  aggressive and we reserve 2% of the entire chip, which is what
  actually manufacturers specify in data sheets.  We introduced an
  option to users to override the default, though.

  There are a couple of fixes as well, and a number of cleanups."

* tag 'upstream-3.7-rc1' of git://git.infradead.org/linux-ubi: (24 commits)
  UBI: fix trivial typo 'it' => 'is'
  UBI: load after mtd device drivers
  UBI: print less
  UBI: use pr_ helper instead of printk
  UBI: comply with coding style
  UBI: erase free PEB with bitflip in EC header
  UBI: fix autoresize handling in R/O mode
  UBI: add max_beb_per1024 to attach ioctl
  UBI: allow specifying bad PEBs limit using module parameter
  UBI: check max_beb_per1024 value in ubi_attach_mtd_dev
  UBI: prepare for max_beb_per1024 module parameter addition
  UBI: introduce MTD_PARAM_MAX_COUNT
  UBI: separate bad_peb_limit in a function
  arm: sam9_l9260_defconfig: correct CONFIG_MTD_UBI_BEB_LIMIT
  UBI: use the whole MTD device size to get bad_peb_limit
  mtd: mtdparts: introduce mtd_get_device_size
  mtd: mark mtd_is_partition argument as constant
  arm: sam9_l9260_defconfig: remove non-existing config option
  UBI: kill CONFIG_MTD_UBI_BEB_RESERVE
  UBI: limit amount of reserved eraseblocks for bad PEB handling
  ...

1 files changed, 27 insertions, 13 deletions

diff --git a/drivers/mtd/ubi/Kconfig b/drivers/mtd/ubi/Kconfig
index ea4b95b5451c..271a842f8c39 100644
--- a/drivers/mtd/ubi/Kconfig
+++ b/drivers/mtd/ubi/Kconfig
@@ -27,20 +27,34 @@ config MTD_UBI_WL_THRESHOLD
 	  life-cycle less than 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"
-	default 2
-	range 0 25
+config MTD_UBI_BEB_LIMIT
+	int "Maximum expected bad eraseblock count per 1024 eraseblocks"
+	default 20
+	range 0 768
 	help
-	  If the MTD device admits of bad eraseblocks (e.g. NAND flash), UBI
-	  reserves some amount of physical eraseblocks to handle new bad
-	  eraseblocks. For example, if a flash physical eraseblock becomes bad,
-	  UBI uses these reserved physical eraseblocks to relocate the bad one.
-	  This option specifies how many physical eraseblocks will be reserved
-	  for bad eraseblock handling (percents of total number of good flash
-	  eraseblocks). If the underlying flash does not admit of bad
-	  eraseblocks (e.g. NOR flash), this value is ignored and nothing is
-	  reserved. Leave the default value if unsure.
+	  This option specifies the maximum bad physical eraseblocks UBI
+	  expects on the MTD device (per 1024 eraseblocks). If the underlying
+	  flash does not admit of bad eraseblocks (e.g. NOR flash), this value
+	  is ignored.
+
+	  NAND datasheets often specify the minimum and maximum NVM (Number of
+	  Valid Blocks) for the flashes' endurance lifetime. The maximum
+	  expected bad eraseblocks per 1024 eraseblocks then can be calculated
+	  as "1024 * (1 - MinNVB / MaxNVB)", which gives 20 for most NANDs
+	  (MaxNVB is basically the total count of eraseblocks on the chip).
+
+	  To put it differently, if this value is 20, UBI will try to reserve
+	  about 1.9% of physical eraseblocks for bad blocks handling. And that
+	  will be 1.9% of eraseblocks on the entire NAND chip, not just the MTD
+	  partition UBI attaches. This means that if you have, say, a NAND
+	  flash chip admits maximum 40 bad eraseblocks, and it is split on two
+	  MTD partitions of the same size, UBI will reserve 40 eraseblocks when
+	  attaching a partition.
+
+	  This option can be overridden by the "mtd=" UBI module parameter or
+	  by the "attach" ioctl.
+
+	  Leave the default value if unsure.
 
 config MTD_UBI_GLUEBI
 	tristate "MTD devices emulation driver (gluebi)"