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UBI: introduce new bad PEB limit 

Introduce 'ubi->bad_peb_limit', which specifies an upper limit of PEBs
UBI expects to go bad.  Currently, it is initialized to a fixed percentage
of total PEBs in the UBI device (configurable via CONFIG_MTD_UBI_BEB_LIMIT).

The 'bad_peb_limit' is intended to be used for calculating the amount of PEBs
UBI needs to reserve for bad eraseblock handling.

Artem: minor amendments.

Signed-off-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@linux.intel.com>
This commit is contained in:
Shmulik Ladkani 2012-07-04 11:06:00 +03:00 committed by Artem Bityutskiy
parent afe7d12b6d
commit 8beeb3bb9d
3 changed files with 32 additions and 8 deletions
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26
drivers/mtd/ubi/Kconfig
View File

@ -34,13 +34,25 @@ config MTD_UBI_BEB_RESERVE
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.
eraseblocks. When a physical eraseblock becomes bad, UBI uses these
reserved physical eraseblocks to relocate the bad one. This
configuration option specifies how many physical eraseblocks will be
reserved for bad eraseblock handling (percents of total number of
good physical eraseblocks on this MTD partition). 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.
config MTD_UBI_BEB_LIMIT
int "Percentage of maximum expected bad eraseblocks"
default 2
range 0 25
help
This option specifies the maximum bad physical eraseblocks UBI
expects on the UBI device (percents of total number of physical
eraseblocks on this MTD partition). If the underlying flash does not
admit of bad eraseblocks (e.g. NOR flash), this value is ignored.
Leave the default value if unsure.
config MTD_UBI_GLUEBI
tristate "MTD devices emulation driver (gluebi)"

12
drivers/mtd/ubi/build.c
View File

@ -607,8 +607,18 @@ static int io_init(struct ubi_device *ubi)
ubi->peb_count = mtd_div_by_eb(ubi->mtd->size, ubi->mtd);
ubi->flash_size = ubi->mtd->size;
if (mtd_can_have_bb(ubi->mtd))
if (mtd_can_have_bb(ubi->mtd)) {
ubi->bad_allowed = 1;
if (CONFIG_MTD_UBI_BEB_LIMIT > 0) {
int percent = CONFIG_MTD_UBI_BEB_LIMIT;
int limit = mult_frac(ubi->peb_count, percent, 100);
/* Round it up */
if (mult_frac(limit, 100, percent) < ubi->peb_count)
limit += 1;
ubi->bad_peb_limit = limit;
}
}
if (ubi->mtd->type == MTD_NORFLASH) {
ubi_assert(ubi->mtd->writesize == 1);

2
drivers/mtd/ubi/ubi.h
View File

@ -363,6 +363,7 @@ struct ubi_wl_entry;
* @flash_size: underlying MTD device size (in bytes)
* @peb_count: count of physical eraseblocks on the MTD device
* @peb_size: physical eraseblock size
* @bad_peb_limit: top limit of expected bad physical eraseblocks
* @bad_peb_count: count of bad physical eraseblocks
* @good_peb_count: count of good physical eraseblocks
* @corr_peb_count: count of corrupted physical eraseblocks (preserved and not
@ -410,6 +411,7 @@ struct ubi_device {
int avail_pebs;
int beb_rsvd_pebs;
int beb_rsvd_level;
int bad_peb_limit;
int autoresize_vol_id;
int vtbl_slots;