From patchwork Wed Oct 10 06:26:06 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [for,3.7] mtd: nand: fix Samsung SLC NAND identification regression Date: Tue, 09 Oct 2012 20:26:06 -0000 From: Brian Norris X-Patchwork-Id: 190556 Message-Id: <1349850366-4731-1-git-send-email-computersforpeace@gmail.com> To: David Woodhouse Cc: Marek Vasut , Brian Norris , linux-mtd@lists.infradead.org, Linux Kernel , Artem Bityutskiy 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 Tested-by: Brian Norris Reported-by: Marek Vasut Tested-by: Marek Vasut --- 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;