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authorScott Wood <scottwood@freescale.com>2008-06-12 13:13:23 -0500
committerScott Wood <scottwood@freescale.com>2008-08-12 11:31:27 -0500
commit984e03cdf1431bb593aeaa1b74c445d616f955d3 (patch)
tree9ca147809a8266bd016050a0789d4b19913d7e40 /doc/README.nand
parente1c3dbada349992875934575c97b328ab2cb33ca (diff)
downloadblackbird-obmc-uboot-984e03cdf1431bb593aeaa1b74c445d616f955d3.tar.gz
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NAND: Always skip blocks on read/write/boot.
Use of the non-skipping versions was almost always (if not always) an error, and no valid use case has been identified. Signed-off-by: Scott Wood <scottwood@freescale.com>
Diffstat (limited to 'doc/README.nand')
-rw-r--r--doc/README.nand37
1 files changed, 12 insertions, 25 deletions
diff --git a/doc/README.nand b/doc/README.nand
index 647a6b8e67..0ad5e18dd3 100644
--- a/doc/README.nand
+++ b/doc/README.nand
@@ -57,14 +57,9 @@ Commands:
Print information about all of the NAND devices found.
nand read addr ofs|partition size
- Read `size' bytes from `ofs' in NAND flash to `addr'. If a page
- cannot be read because it is marked bad or an uncorrectable data
- error is found the command stops with an error.
-
- nand read.jffs2 addr ofs|partition size
- Like `read', but the data for blocks that are marked bad is read as
- 0xff. This gives a readable JFFS2 image that can be processed by
- the JFFS2 commands such as ls and fsload.
+ Read `size' bytes from `ofs' in NAND flash to `addr'. Blocks that
+ are marked bad are skipped. If a page cannot be read because an
+ uncorrectable data error is found, the command stops with an error.
nand read.oob addr ofs|partition size
Read `size' bytes from the out-of-band data area corresponding to
@@ -73,17 +68,15 @@ Commands:
for bad blocks or ECC errors.
nand write addr ofs|partition size
- Write `size' bytes from `addr' to `ofs' in NAND flash. If a page
- cannot be written because it is marked bad or the write fails the
- command stops with an error.
-
- nand write.jffs2 addr ofs|partition size
- Like `write', but blocks that are marked bad are skipped and the
- data is written to the next block instead. This allows writing
- a JFFS2 image, as long as the image is short enough to fit even
- after skipping the bad blocks. Compact images, such as those
- produced by mkfs.jffs2 should work well, but loading an image copied
- from another flash is going to be trouble if there are any bad blocks.
+ Write `size' bytes from `addr' to `ofs' in NAND flash. Blocks that
+ are marked bad are skipped. If a page cannot be read because an
+ uncorrectable data error is found, the command stops with an error.
+
+ As JFFS2 skips blocks similarly, this allows writing a JFFS2 image,
+ as long as the image is short enough to fit even after skipping the
+ bad blocks. Compact images, such as those produced by mkfs.jffs2
+ should work well, but loading an image copied from another flash is
+ going to be trouble if there are any bad blocks.
nand write.oob addr ofs|partition size
Write `size' bytes from `addr' to the out-of-band data area
@@ -215,12 +208,6 @@ JFFS2 related commands:
using both the new code which is able to skip bad blocks
"nand erase clean" additionally writes JFFS2-cleanmarkers in the oob.
- "nand write.jffs2"
- like "nand write" but skip found bad eraseblocks
-
- "nand read.jffs2"
- like "nand read" but skip found bad eraseblocks
-
Miscellaneous and testing commands:
"markbad [offset]"
create an artificial bad block (for testing bad block handling)
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