mtd: nand: make Samsung SLC NAND usable again

BugLink: http://bugs.launchpad.net/bugs/1717549
commit 69fc01296c92814b62dbfba1600fe7ed2ed304f5 upstream.

commit c51d0ac59f24 ("mtd: nand: Move Samsung specific init/detection
logic in nand_samsung.c") introduced a regression for Samsung SLC NAND
chips. Prior to this commit chip->bits_per_cell was initialized by calling
nand_get_bits_per_cell() before using nand_is_slc().
With the offending commit this call is skipped, leaving
chip->bits_per_cell cleared to zero when the manufacturer specific
'.detect' function calls nand_is_slc() which in turn interprets
bits_per_cell != 1 as indication for an MLC chip.
The effect is that e.g. a K9F1G08U0F NAND chip is falsely detected as
MLC NAND with 4KiB page size rather than SLC with 2KiB page size.

Add a call to nand_get_bits_per_cell() before calling the .detect hook
function in nand_manufacturer_detect(), so that the nand_is_slc()
calls in the manufacturer specific code will return correct results.

Fixes: c51d0ac59f24 ("mtd: nand: Move Samsung specific init/detection logic in nand_samsung.c")
Signed-off-by: Lothar Waßmann <LW@KARO-electronics.de>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index c6c18b82f8f4eade18561edb24439a9d4737efa5..c05cf874cbb8e0a8e2ccae9125c5c615d0bea582 100644 (file)
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -3993,10 +3993,13 @@ static void nand_manufacturer_detect(struct nand_chip *chip)
         * nand_decode_ext_id() otherwise.
         */
        if (chip->manufacturer.desc && chip->manufacturer.desc->ops &&
-           chip->manufacturer.desc->ops->detect)
+           chip->manufacturer.desc->ops->detect) {
+               /* The 3rd id byte holds MLC / multichip data */
+               chip->bits_per_cell = nand_get_bits_per_cell(chip->id.data[2]);
                chip->manufacturer.desc->ops->detect(chip);
-       else
+       } else {
                nand_decode_ext_id(chip);
+       }
 }
 
 /*