A combination of the following two commits caused a regression in 3.7-rc1
when identifying some Samsung NAND, so that some previously working NAND
were no longer detected properly:
commit e3b88bd604283ef83ae6e8f53622d5b1ffe9d43a
mtd: nand: add generic READ ID length calculation functions
commit e2d3a35ee427aaba99b6c68a56609ce276c51270
mtd: nand: detect Samsung K9GBG08U0A, K9GAG08U0F ID
Particularly, a regression was seen on Samsung K9F2G08U0B, with the
following full 8-byte READ ID string:
ec da 10 95 44 00 ec da
The basic problem is that Samsung manufactures both SLC and MLC NAND
that use a non-standard decoding table for deriving information from
their IDs. I have heuristically determined that all the chips that use
the new table have ID strings which wrap around after the 6th byte.
Unfortunately, I overlooked the fact that some older Samsung SLC (which
use a different decoding table) have "5 byte ID strings" which also wrap
around after the 6th byte.
This patch re-introduces a distinction between these old and new Samsung
NAND by checking that the 6th byte is non-zero, allowing both old and
new Samsung NAND to be detected properly.
Signed-off-by: Brian Norris <computersforpe...@gmail.com>
Tested-by: Brian Norris <computersforpe...@gmail.com>
Reported-by: Marek Vasut <ma...@denx.de>
Tested-by: Marek Vasut <ma...@denx.de>
---
David,
Marek and I just discovered this issue during the merge window. Please merge
this fix in the 3.7-rc cycle. Thanks.
drivers/mtd/nand/nand_base.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index ec6841d..d5ece6e 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -2983,13 +2983,14 @@ static void nand_decode_ext_id(struct mtd_info *mtd,
struct nand_chip *chip,
/*
* Field definitions are in the following datasheets:
* Old style (4,5 byte ID): Samsung K9GAG08U0M (p.32)
- * New style (6 byte ID): Samsung K9GAG08U0F (p.44)
+ * New Samsung (6 byte ID): Samsung K9GAG08U0F (p.44)
* Hynix MLC (6 byte ID): Hynix H27UBG8T2B (p.22)
*
- * Check for ID length, cell type, and Hynix/Samsung ID to decide what
- * to do.
+ * Check for ID length, non-zero 6th byte, cell type, and Hynix/Samsung
+ * ID to decide what to do.
*/
- if (id_len == 6 && id_data[0] == NAND_MFR_SAMSUNG) {
+ if (id_len == 6 && id_data[0] == NAND_MFR_SAMSUNG &&
+ id_data[5] != 0x00) {
/* Calc pagesize */
mtd->writesize = 2048 << (extid & 0x03);
extid >>= 2;
--
1.7.11.3
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