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authorWhite Ding <bpqw@micron.com>2018-11-14 12:04:27 +0100
committerSascha Hauer <s.hauer@pengutronix.de>2018-11-16 08:33:13 +0100
commit1bce5f39c2ce0c79f0769f2e69d5e9caed28dfc2 (patch)
treec4b5039a6b50b0dfd8e3764026e21012ad7d5abc
parent45af01d16dbaabd918c141fcb7dcd7efeeac7c07 (diff)
downloadbarebox-1bce5f39c2ce0c79f0769f2e69d5e9caed28dfc2.tar.gz
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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> [Cherry-picked from linux: 57d3a9a89a06 mtd: nand: fix nand_lock/unlock() function] Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
-rw-r--r--drivers/mtd/nand/nand_base.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index ccf9615042..128802fa5c 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -852,6 +852,15 @@ 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",
@@ -902,6 +911,15 @@ 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",