[PATCH] mtd: gpmi: fix the ecc regression

[Huang Shijie]

The patch "2febcdf mtd: gpmi: set the BCHs geometry with the ecc info"
makes the gpmi to use the ECC info provided by the MTD code, and creates
a different NAND ecc layout for the BCH which brings a regression to us:
   We can not mount the ubifs which was created by the old NAND ecc layout.

This patch adds a new property : "fsl,use-mtd-ecc-info".

If we do not enable it, we will use the ecc strength calculated by ourselves
and use all the OOB area (this is the legacy method);

If we enable it, we will use the ecc strength provided by the MTD layer,
and create a new NAND ecc layout which may has free space in the OOB
(for some SLC nand, we may support the JFFS2 with the new NAND ecc layout).

Signed-off-by: Huang Shijie <b32955 at freescale.com>
---
 .../devicetree/bindings/mtd/gpmi-nand.txt          |    4 ++++
 drivers/mtd/nand/gpmi-nand/gpmi-nand.c             |    7 ++++++-
 2 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/Documentation/devicetree/bindings/mtd/gpmi-nand.txt b/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
index 551b2a1..fe84a3d 100644
--- a/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
+++ b/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
@@ -17,6 +17,10 @@ Required properties:
 Optional properties:
   - nand-on-flash-bbt: boolean to enable on flash bbt option if not
                        present false
+  - fsl,use-mtd-ecc-info: By enabling this boolean property, the gpmi can uses
+                       the MTD's ECC info (if the MTD has). So we may have free
+                       space in the OOB area, and we may support the JFFS2 with
+                       some SLC nand, such as Micron's SLC nand.
 
 The device tree may optionally contain sub-nodes describing partitions of the
 address space. See partition.txt for more detail.
diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
index 5a1bbc7..62c0712 100644
--- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
@@ -271,7 +271,9 @@ static int legacy_set_geometry(struct gpmi_nand_data *this)
 		dev_err(this->dev,
 			"We can not support this nand chip."
 			" Its required ecc strength(%d) is beyond our"
-			" capability(%d).\n", geo->ecc_strength,
+			" capability(%d). If you have not enabled the"
+			"'fsl,use-mtd-ecc-info', enable it and try again.\n",
+			geo->ecc_strength,
 			(GPMI_IS_MX6Q(this) ? MX6_ECC_STRENGTH_MAX
 					: MXS_ECC_STRENGTH_MAX));
 		return -EINVAL;
@@ -352,6 +354,9 @@ static int legacy_set_geometry(struct gpmi_nand_data *this)
 
 int common_nfc_set_geometry(struct gpmi_nand_data *this)
 {
+	if (!of_property_read_bool(this->dev->of_node, "fsl,use-mtd-ecc-info"))
+		return legacy_set_geometry(this);
+
 	return set_geometry_by_ecc_info(this) ? 0 : legacy_set_geometry(this);
 }
 
-- 
1.7.2.rc3