[PATCH] mtd: Edit comments on deprecation of ioctl ECCGETLAYOUT

Brian Norris
2010-09-20T06:57:15Z

** Applies to l2-mtd-2.6.git: master **

There were some improvements and additions necessary in the
comments explaining of the expansion of nand_ecclayout, the
introduction of nand_ecclayout_user, and the deprecation of the
ioctl ECCGETLAYOUT.

Also, I found a better placement for the macro MTD_MAX_ECCPOS_ENTRIES;
next to the definition of MTD_MAX_OOBFREE_ENTRIES in mtd-abi.h. The macro
is really only important for the ioctl code (found in drivers/mtd/mtdchar.c)
but since there are small edits being made to the user-space header, I
figured this is a better location.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
---
drivers/mtd/mtdchar.c | 2 +-
include/linux/mtd/mtd.h | 8 ++++----
include/mtd/mtd-abi.h | 11 ++++++++---
3 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index 44868cf..5895de7 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -495,7 +495,7 @@ static int shrink_ecclayout(const struct nand_ecclayout *from,

memset(to, 0, sizeof(*to));

- to->eccbytes = min((int)from->eccbytes, MTD_MAX_ECCPOS_ENTRIES_OLD);
+ to->eccbytes = min((int)from->eccbytes, MTD_MAX_ECCPOS_ENTRIES);
for (i = 0; i < to->eccbytes; i++)
to->eccpos[i] = from->eccpos[i];

diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index 03a1e95..fe8d77e 100644
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -112,11 +112,11 @@ struct mtd_oob_ops {

#define MTD_MAX_OOBFREE_ENTRIES_LARGE 32
#define MTD_MAX_ECCPOS_ENTRIES_LARGE 448
-#define MTD_MAX_ECCPOS_ENTRIES_OLD 64 /* Previous maximum */
/*
- * Correct ECC layout control structure. This replaces old nand_ecclayout
- * (mtd-abi.h) that is exported via ECCGETLAYOUT ioctl. It should be expandable
- * in the future simply by the above macros.
+ * Internal ECC layout control structure. For historical reasons, there is a
+ * similar, smaller struct nand_ecclayout_user (in mtd-abi.h) that is retained
+ * for export to user-space via the ECCGETLAYOUT ioctl.
+ * nand_ecclayout should be expandable in the future simply by the above macros.
*/
struct nand_ecclayout {
__u32 eccbytes;
diff --git a/include/mtd/mtd-abi.h b/include/mtd/mtd-abi.h
index 5bce083..a57c4cb 100644
--- a/include/mtd/mtd-abi.h
+++ b/include/mtd/mtd-abi.h
@@ -144,13 +144,18 @@ struct nand_oobfree {
};

#define MTD_MAX_OOBFREE_ENTRIES 8
+#define MTD_MAX_ECCPOS_ENTRIES 64
/*
- * ECC layout control structure. Exported to userspace for
- * diagnosis and to allow creation of raw images
+ * OBSOLETE: ECC layout control structure. Exported to user-space via ioctl
+ * ECCGETLAYOUT for backwards compatbility and should not be mistaken as a
+ * complete set of ECC information. The ioctl truncates the larger internal
+ * structure to retain binary compatibility with the static declaration of the
+ * ioctl. Note that the "MTD_MAX_..._ENTRIES" macros represent the max size of
+ * the user struct, not the MAX size of the internal struct nand_ecclayout.
*/
struct nand_ecclayout_user {
__u32 eccbytes;
- __u32 eccpos[64];
+ __u32 eccpos[MTD_MAX_ECCPOS_ENTRIES];
__u32 oobavail;
struct nand_oobfree oobfree[MTD_MAX_OOBFREE_ENTRIES];
};
--
1.7.0.4