This patch provides the possibility to adjust the "maximum expected number of
bad blocks per 1024 blocks" (max_beb_per1024) for each mtd device.

The majority of NAND devices have their max_beb_per1024 equal to 20, but
sometimes it's more.
Now, we can adjust that via a kernel parameter:
ubi.mtd=<name|num|path>[,<vid_hdr_offs>[,max_beb_per1024]]

Signed-off-by: Richard Genoud <[email protected]>
---
 drivers/mtd/ubi/Kconfig |    2 ++
 drivers/mtd/ubi/build.c |   38 ++++++++++++++++++++++++--------------
 2 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/drivers/mtd/ubi/Kconfig b/drivers/mtd/ubi/Kconfig
index f326877..8b67bac 100644
--- a/drivers/mtd/ubi/Kconfig
+++ b/drivers/mtd/ubi/Kconfig
@@ -51,6 +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.
+
          Leave the default value if unsure.
 
 config MTD_UBI_GLUEBI
diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index ec7311f..cc05022 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -47,7 +47,7 @@
 #define MTD_PARAM_LEN_MAX 64
 
 /* Maximum number of comma-separated items in ht 'mtd=' parameter */
-#define MTD_PARAM_MAX_COUNT 2
+#define MTD_PARAM_MAX_COUNT 3
 
 #ifdef CONFIG_MTD_UBI_MODULE
 #define ubi_is_module() 1
@@ -60,10 +60,12 @@
  * @name: MTD character device node path, MTD device name, or MTD device number
  *        string
  * @vid_hdr_offs: VID header offset
+ * @max_beb_per1024: maximum expected number of bad blocks per 1024 erase 
blocks
  */
 struct mtd_dev_param {
        char name[MTD_PARAM_LEN_MAX];
        int vid_hdr_offs;
+       int max_beb_per1024;
 };
 
 /* Numbers of elements set in the @mtd_dev_param array */
@@ -1222,8 +1224,7 @@ static int __init ubi_init(void)
 
                mutex_lock(&ubi_devices_mutex);
                err = ubi_attach_mtd_dev(mtd, UBI_DEV_NUM_AUTO,
-                                        p->vid_hdr_offs,
-                                        CONFIG_MTD_UBI_BEB_LIMIT);
+                                        p->vid_hdr_offs, p->max_beb_per1024);
                mutex_unlock(&ubi_devices_mutex);
                if (err < 0) {
                        ubi_err("cannot attach mtd%d", mtd->index);
@@ -1343,6 +1344,7 @@ static int __init ubi_mtd_param_parse(const char *val, 
struct kernel_param *kp)
        char buf[MTD_PARAM_LEN_MAX];
        char *pbuf = &buf[0];
        char *tokens[MTD_PARAM_MAX_COUNT];
+       int err;
 
        if (!val)
                return -EINVAL;
@@ -1390,23 +1392,31 @@ static int __init ubi_mtd_param_parse(const char *val, 
struct kernel_param *kp)
        if (p->vid_hdr_offs < 0)
                return p->vid_hdr_offs;
 
+       if (tokens[2]) {
+               err = kstrtoint(tokens[2], 10, &p->max_beb_per1024);
+               if (err) {
+                       pr_err("UBI error: bad value for max_beb_per1024 
parameter: %s",
+                              tokens[2]);
+                       return -EINVAL;
+               }
+       }
+
        mtd_devs += 1;
        return 0;
 }
 
 module_param_call(mtd, ubi_mtd_param_parse, NULL, NULL, 000);
-MODULE_PARM_DESC(mtd, "MTD devices to attach. Parameter format: "
-                     "mtd=<name|num|path>[,<vid_hdr_offs>].\n"
+MODULE_PARM_DESC(mtd, "MTD devices to attach. Parameter format: 
mtd=<name|num|path>[,<vid_hdr_offs>[,max_beb_per1024]].\n"
                      "Multiple \"mtd\" parameters may be specified.\n"
-                     "MTD devices may be specified by their number, name, or "
-                     "path to the MTD character device node.\n"
-                     "Optional \"vid_hdr_offs\" parameter specifies UBI VID "
-                     "header position to be used by UBI.\n"
-                     "Example 1: mtd=/dev/mtd0 - attach MTD device "
-                     "/dev/mtd0.\n"
-                     "Example 2: mtd=content,1984 mtd=4 - attach MTD device "
-                     "with name \"content\" using VID header offset 1984, and "
-                     "MTD device number 4 with default VID header offset.");
+                     "MTD devices may be specified by their number, name, or 
path to the MTD character device node.\n"
+                     "Optional \"vid_hdr_offs\" parameter specifies UBI VID 
header position to be used by UBI. (default value if 0 or not set)\n"
+                     "Optional \"max_beb_per1024\" parameter specifies the 
maximum expected bad eraseblock per 1024 eraseblocks. (default value ("
+                     __stringify(CONFIG_MTD_UBI_BEB_LIMIT) ") if 0 or not 
set)\n"
+                     "\n"
+                     "Example 1: mtd=/dev/mtd0 - attach MTD device 
/dev/mtd0.\n"
+                     "Example 2: mtd=content,1984 mtd=4 - attach MTD device 
with name \"content\" using VID header offset 1984, and MTD device number 4 
with default VID header offset.\n"
+                     "Example 3: mtd=/dev/mtd1,0,25 - attach MTD device 
/dev/mtd1 using default VID header offset and reserve 
25*nand_size_in_blocks/1024 erase blocks for bad block handling.\n"
+                     "\t(e.g. if the NAND *chipset* has 4096 PEB, 100 will be 
reserved for this UBI device).");
 
 MODULE_VERSION(__stringify(UBI_VERSION));
 MODULE_DESCRIPTION("UBI - Unsorted Block Images");
-- 
1.7.2.5

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