Hi Scott,

On Dec 11, 2012, at 12:53 AM, Scott Wood wrote:

On 12/10/2012 09:24:24 AM, Pantelis Antoniou wrote:

...

When accessing nand any bad blocks encountered are skipped, with no indication about the amount of bad blocks encountered. While this is normally fine, when you have to write a large amount of data in chunks, you need to account for the skipped amount due to the presence of the bad blocks. nand_extend_skip_bad() returns the offset where the next access should occur.

s/extend/extent/

Yeah.

...

Signed-off-by: Pantelis Antoniou panto@antoniou-consulting.com

drivers/mtd/nand/nand_util.c | 50 ++++++++++++++++++++++++++++++++++++++++++++ include/nand.h | 2 ++ 2 files changed, 52 insertions(+) diff --git a/drivers/mtd/nand/nand_util.c b/drivers/mtd/nand/nand_util.c index 2ba0c5e..a25a4cb 100644 --- a/drivers/mtd/nand/nand_util.c +++ b/drivers/mtd/nand/nand_util.c @@ -684,6 +684,56 @@ int nand_read_skip_bad(nand_info_t *nand, loff_t offset, size_t *length, return 0; } +/**

• • nand_extent_skip_bad:
• • Find the extent of a chunk, return the offset where it ends
• • Blocks that are marked bad are skipped and the next block is examined
• • instead as long as the extend is short enough to fit even after skipping the
• • bad blocks.
• • @param nand NAND device
• • @param offset offset in flash
• • @param length extend length
• • @return next offset in case of success (loff_t)-1 on error
• */

Would it be better to return this information from existing read/write functions -- either instead of or in addition to exporting this functionality?

Yes it would. However that would require modifying all callers, which would be a hard sell when there's only one user of it.

...

+loff_t nand_extent_skip_bad(nand_info_t *nand, loff_t offset, size_t length) +{

• size_t block_len, block_off;
• loff_t block_start;
• if ((offset & (nand->writesize - 1)) != 0) {

• printf ("%s: Attempt to check extend non page aligned data\n",
  

• 		__func__);
  

• return (loff_t)-1;
  

• }
• while (length > 0) {

• if (offset >= nand->size) {
  

• 	printf("%s: offset >= nand->size (%llx >= %llx)\n",
  

• 			__func__, offset, nand->size);
  

• 	return (loff_t)-1;
  

• }
  

• block_start = offset & ~(loff_t)(nand->erasesize - 1);
  

• block_off = offset & (nand->erasesize - 1);
  

• block_len = nand->erasesize - block_off;
  

• if (block_len > length)		/* left over */
  

• 	block_len = length;
  

• if (!nand_block_isbad(nand, block_start))
  

• 	length -= block_len;
  

• else
  

• 	debug("%s: bad block at %llx (left %x)\n",
  

• 			__func__, block_start, length);
  

• offset += block_len;
  

• }
• return offset;

+}

This seems duplicative of check_skip_len().

It is. check_skip_len doesn't return the information I need. I could modify check_skip_len with an extra parameter if that's going to be OK with you.

-Scott

Regards

-- Pantelis