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Date:	Thu, 24 Jul 2014 01:00:01 +0000
From:	bpqw <bpqw@...ron.com>
To:	"dwmw2@...radead.org" <dwmw2@...radead.org>,
	"computersforpeace@...il.com" <computersforpeace@...il.com>
CC:	"b32955@...escale.com" <b32955@...escale.com>,
	"artem.bityutskiy@...ux.intel.com" <artem.bityutskiy@...ux.intel.com>,
	"ron@...ian.org" <ron@...ian.org>,
	"u.kleine-koenig@...gutronix.de" <u.kleine-koenig@...gutronix.de>,
	"ezequiel.garcia@...e-electrons.com" 
	<ezequiel.garcia@...e-electrons.com>,
	"linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Subject: [PATCH 1/1] 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.

Signed-off-by: White Ding <bpqw@...ron.com>
---
 drivers/mtd/nand/nand_base.c |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 41167e9..22dd3aa 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -965,6 +965,15 @@ 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",
@@ -1015,6 +1024,15 @@ 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",
-- 
1.7.9.5

Br
White Ding 
____________________________
EBU APAC Application Engineering
Tel:86-21-38997078
Mobile: 86-13761729112
Address: No 601 Fasai Rd, Waigaoqiao Free Trade Zone Pudong, Shanghai, China

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