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    Subject[PATCH 7/8] UBI: add ioctl for max_beb_per1024
    Date
    This patch provides the possibility to adjust the "maximum expected number of
    bad blocks per 1024 blocks" (max_beb_per1024) for each mtd device from
    UBI_IOCATT ioctl.

    The majority of NAND devices have their max_beb_per1024 equal to 20, but
    sometimes it's more.
    We already could adjust that via a kernel parameter, now we can also use
    UBI_IOCATT ioctl:
    struct ubi_attach_req {
    __s32 ubi_num;
    __s32 mtd_num;
    __s32 vid_hdr_offset;
    __u8 max_beb_per1024;
    __s8 padding[11];
    };

    Signed-off-by: Richard Genoud <richard.genoud@gmail.com>
    ---
    drivers/mtd/ubi/Kconfig | 3 ++-
    drivers/mtd/ubi/cdev.c | 2 +-
    include/mtd/ubi-user.h | 19 ++++++++++++++++++-
    3 files changed, 21 insertions(+), 3 deletions(-)

    diff --git a/drivers/mtd/ubi/Kconfig b/drivers/mtd/ubi/Kconfig
    index 8b67bac..56531a7 100644
    --- a/drivers/mtd/ubi/Kconfig
    +++ b/drivers/mtd/ubi/Kconfig
    @@ -51,7 +51,8 @@ config MTD_UBI_BEB_LIMIT
    MTD partitions of the same size, UBI will reserve 40 eraseblocks when
    attaching a partition.

    - This option can be overridden by the kernel parameter ubi.mtd.
    + This option can be overridden by the kernel parameter ubi.mtd and the
    + ioctl UBI_IOCATT.

    Leave the default value if unsure.

    diff --git a/drivers/mtd/ubi/cdev.c b/drivers/mtd/ubi/cdev.c
    index 619f914..7885dc0 100644
    --- a/drivers/mtd/ubi/cdev.c
    +++ b/drivers/mtd/ubi/cdev.c
    @@ -1011,7 +1011,7 @@ static long ctrl_cdev_ioctl(struct file *file, unsigned int cmd,
    */
    mutex_lock(&ubi_devices_mutex);
    err = ubi_attach_mtd_dev(mtd, req.ubi_num, req.vid_hdr_offset,
    - CONFIG_MTD_UBI_BEB_LIMIT);
    + req.max_beb_per1024);
    mutex_unlock(&ubi_devices_mutex);
    if (err < 0)
    put_mtd_device(mtd);
    diff --git a/include/mtd/ubi-user.h b/include/mtd/ubi-user.h
    index 8787349..8168d9b 100644
    --- a/include/mtd/ubi-user.h
    +++ b/include/mtd/ubi-user.h
    @@ -222,6 +222,7 @@ 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 bad eraseblocks per 1024 eraseblocks
    * @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
    @@ -245,12 +246,28 @@ 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 bad eraseblocks 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 0-255. If 0 is given, the default kernel config value
    + * CONFIG_MTD_UBI_BEB_LIMIT will be used for compatibility.
    */
    struct ubi_attach_req {
    __s32 ubi_num;
    __s32 mtd_num;
    __s32 vid_hdr_offset;
    - __s8 padding[12];
    + __u8 max_beb_per1024;
    + __s8 padding[11];
    };

    /**
    --
    1.7.2.5


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