ubi-user.h: add max_beb_per1024 parameter

Signed-off-by: Richard Genoud <richard.genoud@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

diff --git a/include/mtd/ubi-user.h b/include/mtd/ubi-user.h
index 19762d09ad74e3c9631e8e10784dda7ab0f9cca8..1c06d8858e43fcc2c0c5c509d4681a62315bb779 100644 (file)
--- a/include/mtd/ubi-user.h
+++ b/include/mtd/ubi-user.h
@@ -220,6 +220,7 @@ enum {
  * @ubi_num: UBI device number to create
  * @mtd_num: MTD device number to attach
  * @vid_hdr_offset: VID header offset (use defaults if %0)
+ * @max_beb_per1024: maximum expected number of bad PEB per 1024 PEBs
  * @padding: reserved for future, not used, has to be zeroed
  *
  * This data structure is used to specify MTD device UBI has to attach and the
@@ -243,12 +244,25 @@ enum {
  * be 2KiB-64 bytes = 1984. Note, that this position is not even 512-bytes
  * aligned, which is OK, as UBI is clever enough to realize this is 4th
  * sub-page of the first page and add needed padding.
+ *
+ * The @max_beb_per1024 is the maximum amount of bad PEBs UBI expects on the
+ * UBI device per 1024 eraseblocks.  This value is often given in an other form
+ * in the NAND datasheet (min NVB i.e. minimal number of valid blocks). The
+ * maximum expected bad eraseblocks per 1024 is then:
+ *    1024 * (1 - MinNVB / MaxNVB)
+ * Which gives 20 for most NAND devices.  This limit is used in order to derive
+ * amount of eraseblock UBI reserves for handling new bad blocks. If the device
+ * has more bad eraseblocks than this limit, UBI does not reserve any physical
+ * eraseblocks for new bad eraseblocks, but attempts to use available
+ * eraseblocks (if any). The accepted range is 0-768. If 0 is given, the
+ * default kernel value of %CONFIG_MTD_UBI_BEB_LIMIT will be used.
  */
 struct ubi_attach_req {
        int32_t ubi_num;
        int32_t mtd_num;
        int32_t vid_hdr_offset;
-       int8_t padding[12];
+       int16_t max_beb_per1024;
+       int8_t  padding[10];
 };
 
 /**