diff options
| author | White Ding <bpqw@micron.com> | 2014-07-23 18:10:45 +0200 |
|---|---|---|
| committer | Brian Norris <computersforpeace@gmail.com> | 2014-08-19 20:53:07 +0200 |
| commit | 57d3a9a89a0645f3597561e214f8d6852a2c56b4 (patch) | |
| tree | 301383669e65312665f6c01820884bdb10ba3ee0 /drivers/mtd | |
| parent | mtd: Fixed checkpatch seq_printf warnings (diff) | |
| download | linux-57d3a9a89a0645f3597561e214f8d6852a2c56b4.tar.xz linux-57d3a9a89a0645f3597561e214f8d6852a2c56b4.zip | |
mtd: nand: fix nand_lock/unlock() function
Do nand reset before write protect check.
If we want to check the WP# low or high through STATUS READ and check bit 7,
we must reset the device, other operation (eg.erase/program a locked block) can
also clear the bit 7 of status register.
As we know the status register can be refreshed, if we do some operation to trigger it,
for example if we do erase/program operation to one block that is locked, then READ STATUS,
the bit 7 of READ STATUS will be 0 indicate the device in write protect, then if we do
erase/program operation to another block that is unlocked, the bit 7 of READ STATUS will
be 1 indicate the device is not write protect.
Suppose we checked the bit 7 of READ STATUS is 0 then judge the WP# is low (write protect),
but in this case the WP# maybe high if we do erase/program operation to a locked block,
so we must reset the device if we want to check the WP# low or high through STATUS READ and
check bit 7.
Signed-off-by: White Ding <bpqw@micron.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Diffstat (limited to 'drivers/mtd')
| -rw-r--r-- | drivers/mtd/nand/nand_base.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c index d8cdf06343fb..1a27c2da29ff 100644 --- a/drivers/mtd/nand/nand_base.c +++ b/drivers/mtd/nand/nand_base.c @@ -982,6 +982,15 @@ int nand_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len) chip->select_chip(mtd, chipnr); + /* + * Reset the chip. + * If we want to check the WP through READ STATUS and check the bit 7 + * we must reset the chip + * some operation can also clear the bit 7 of status register + * eg. erase/program a locked block + */ + chip->cmdfunc(mtd, NAND_CMD_RESET, -1, -1); + /* Check, if it is write protected */ if (nand_check_wp(mtd)) { pr_debug("%s: device is write protected!\n", @@ -1032,6 +1041,15 @@ int nand_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len) chip->select_chip(mtd, chipnr); + /* + * Reset the chip. + * If we want to check the WP through READ STATUS and check the bit 7 + * we must reset the chip + * some operation can also clear the bit 7 of status register + * eg. erase/program a locked block + */ + chip->cmdfunc(mtd, NAND_CMD_RESET, -1, -1); + /* Check, if it is write protected */ if (nand_check_wp(mtd)) { pr_debug("%s: device is write protected!\n", |