[PATCH] mtd: Apply Numonyx Axcell P33/P30 workaround for Lock/Unlock bug.

[Philippe De Muyter]

    Some flash chips have a small but annoying bug, documented in
    "Numonyx Axcell P33/P30 256-Mbit Specification Update"

    It states :
    When customer uses [...] block unlock, the block lock status might
    be altered inadvertently. Lock status might be set to either 01h
    or 03h unexpectedly (00h as expected data), which leads to
    program/erase failure on certain blocks.

    A workaround is given, (summary : issue a "Read Lock Status" before
    the "Lock" or "Unlock" command) which I have applied and tested
    with success.

Signed-off-by: Philippe De Muyter <phdm at macqel.be>
---
 drivers/mtd/chips/cfi_cmdset_0001.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/drivers/mtd/chips/cfi_cmdset_0001.c b/drivers/mtd/chips/cfi_cmdset_0001.c
index 9e2b7e9..0d0ae41 100644
--- a/drivers/mtd/chips/cfi_cmdset_0001.c
+++ b/drivers/mtd/chips/cfi_cmdset_0001.c
@@ -2047,6 +2047,7 @@ static int __xipram do_xxlock_oneblock(struct map_info *map, struct flchip *chip
 {
 	struct cfi_private *cfi = map->fldrv_priv;
 	struct cfi_pri_intelext *extp = cfi->cmdset_priv;
+	int ofs_factor = cfi->interleave * cfi->device_type;
 	int udelay;
 	int ret;
 
@@ -2062,6 +2063,14 @@ static int __xipram do_xxlock_oneblock(struct map_info *map, struct flchip *chip
 	ENABLE_VPP(map);
 	xip_disable(map, chip, adr);
 
+	/*
+	 * Issue a "Read Lock Status" before the "Lock" or "Unlock" :
+	 * see errata "Numonyx Axcell P33/P30 Specification Update" :)
+	 */
+	map_write(map, CMD(0x90), adr+(2*ofs_factor));
+	chip->state = FL_JEDEC_QUERY;
+	cfi_read_query(map, adr+(2*ofs_factor));
+
 	map_write(map, CMD(0x60), adr);
 	if (thunk == DO_XXLOCK_ONEBLOCK_LOCK) {
 		map_write(map, CMD(0x01), adr);
-- 
1.7.1