>Hi

>I have review the yaffs2 source code and have a doubt. See the follow



>In Yaffs2 the read interface is yaffs_rd_chunk_tags_nand int yaffs_rd_chunk_tags_nand(struct yaffs_dev *dev, int nand_chunk,

>                       u8 *buffer, struct yaffs_ext_tags *tags) {

>      .........

>      result = dev->tagger.read_chunk_tags_fn(dev, flash_chunk, buffer, tags);

>      if (tags && tags->ecc_result > YAFFS_ECC_RESULT_NO_ERROR) {

>

>            struct yaffs_block_info *bi;

>            bi = yaffs_get_block_info(dev,

>                                nand_chunk /

>                                dev->param.chunks_per_block);

>            yaffs_handle_chunk_error(dev, bi);

>      }

>      return result;

>}

>

>The yaffs_rd_chunk_tags_nand will call the mtd interface mtd_read_oob



>int mtd_read_oob(struct mtd_info *mtd, loff_t from, struct mtd_oob_ops *ops) {

>      int ret_code;

>      ops->retlen = ops->oobretlen = 0;

>      if (!mtd->_read_oob)

>            return -EOPNOTSUPP;

>      /*

>      * In cases where ops->datbuf != NULL, mtd->_read_oob() has semantics

>      * similar to mtd->_read(), returning a non-negative integer

>      * representing max bitflips. In other cases, mtd->_read_oob() may

>      * return -EUCLEAN. In all cases, perform similar logic to mtd_read().

>      */

>      ret_code = mtd->_read_oob(mtd, from, ops);

>      if (unlikely(ret_code < 0))

>            return ret_code;

>      if (mtd->ecc_strength == 0)

>            return 0;   /* device lacks ecc */

>      return ret_code >= mtd->bitflip_threshold ? -EUCLEAN : 0; }



>So if the bitflips num over mtd->bitflip_threshold the mtd_read_oob will return -EUCLEAN and tags->ecc_result > YAFFS_ECC_RESULT_NO_ERROR.>

>Then we will call yaffs_handle_chunk_error.

>void yaffs_handle_chunk_error(struct yaffs_dev *dev,

>                        struct yaffs_block_info *bi)

>{

>      if (!bi->gc_prioritise) {

>            bi->gc_prioritise = 1;

>            dev->has_pending_prioritised_gc = 1;

>            bi->chunk_error_strikes++;

>

>            if (bi->chunk_error_strikes > 3) {

>                  bi->needs_retiring = 1; /* Too many stikes, so retire */

>                  yaffs_trace(YAFFS_TRACE_ALWAYS,

>                        "yaffs: Block struck out");

>

>            }

>      }

>}



>From the code we can see if bitflips num over mtd->bitflip_threshold we will mark this block as gc if bitflips num over mtd->bitflip_threshold over three times we will mark this block as bad block.



>We define bad block is if erase or program failed we can mark this block as bad block.

>So is it reasonable just according to the bitflips over mtd->bitflip_threshold over three times to judge the block as bad block?

>What's your opinion about my doubts?



Hi clarles,

Do you have any proposal about this?


Br
White Ding
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