Merge branch 'for-next/mtd'
This commit is contained in:
commit
2881f2df35
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@ -906,6 +906,134 @@ out:
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}
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EXPORT_SYMBOL(nand_lock);
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/**
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* nand_check_erased_buf - check if a buffer contains (almost) only 0xff data
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* @buf: buffer to test
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* @len: buffer length
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* @bitflips_threshold: maximum number of bitflips
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*
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* Check if a buffer contains only 0xff, which means the underlying region
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* has been erased and is ready to be programmed.
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* The bitflips_threshold specify the maximum number of bitflips before
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* considering the region is not erased.
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* Note: The logic of this function has been extracted from the memweight
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* implementation, except that nand_check_erased_buf function exit before
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* testing the whole buffer if the number of bitflips exceed the
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* bitflips_threshold value.
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*
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* Returns a positive number of bitflips less than or equal to
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* bitflips_threshold, or -ERROR_CODE for bitflips in excess of the
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* threshold.
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*/
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static int nand_check_erased_buf(void *buf, int len, int bitflips_threshold)
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{
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const unsigned char *bitmap = buf;
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int bitflips = 0;
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int weight;
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for (; len && ((uintptr_t)bitmap) % sizeof(long);
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len--, bitmap++) {
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weight = hweight8(*bitmap);
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bitflips += BITS_PER_BYTE - weight;
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if (unlikely(bitflips > bitflips_threshold))
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return -EBADMSG;
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}
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for (; len >= sizeof(long);
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len -= sizeof(long), bitmap += sizeof(long)) {
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weight = hweight_long(*((unsigned long *)bitmap));
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bitflips += BITS_PER_LONG - weight;
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if (unlikely(bitflips > bitflips_threshold))
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return -EBADMSG;
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}
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for (; len > 0; len--, bitmap++) {
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weight = hweight8(*bitmap);
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bitflips += BITS_PER_BYTE - weight;
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if (unlikely(bitflips > bitflips_threshold))
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return -EBADMSG;
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}
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return bitflips;
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}
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/**
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* nand_check_erased_ecc_chunk - check if an ECC chunk contains (almost) only
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* 0xff data
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* @data: data buffer to test
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* @datalen: data length
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* @ecc: ECC buffer
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* @ecclen: ECC length
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* @extraoob: extra OOB buffer
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* @extraooblen: extra OOB length
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* @bitflips_threshold: maximum number of bitflips
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*
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* Check if a data buffer and its associated ECC and OOB data contains only
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* 0xff pattern, which means the underlying region has been erased and is
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* ready to be programmed.
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* The bitflips_threshold specify the maximum number of bitflips before
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* considering the region as not erased.
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*
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* Note:
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* 1/ ECC algorithms are working on pre-defined block sizes which are usually
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* different from the NAND page size. When fixing bitflips, ECC engines will
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* report the number of errors per chunk, and the NAND core infrastructure
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* expect you to return the maximum number of bitflips for the whole page.
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* This is why you should always use this function on a single chunk and
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* not on the whole page. After checking each chunk you should update your
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* max_bitflips value accordingly.
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* 2/ When checking for bitflips in erased pages you should not only check
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* the payload data but also their associated ECC data, because a user might
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* have programmed almost all bits to 1 but a few. In this case, we
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* shouldn't consider the chunk as erased, and checking ECC bytes prevent
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* this case.
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* 3/ The extraoob argument is optional, and should be used if some of your OOB
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* data are protected by the ECC engine.
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* It could also be used if you support subpages and want to attach some
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* extra OOB data to an ECC chunk.
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*
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* Returns a positive number of bitflips less than or equal to
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* bitflips_threshold, or -ERROR_CODE for bitflips in excess of the
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* threshold. In case of success, the passed buffers are filled with 0xff.
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*/
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int nand_check_erased_ecc_chunk(void *data, int datalen,
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void *ecc, int ecclen,
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void *extraoob, int extraooblen,
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int bitflips_threshold)
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{
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int data_bitflips = 0, ecc_bitflips = 0, extraoob_bitflips = 0;
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data_bitflips = nand_check_erased_buf(data, datalen,
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bitflips_threshold);
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if (data_bitflips < 0)
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return data_bitflips;
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bitflips_threshold -= data_bitflips;
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ecc_bitflips = nand_check_erased_buf(ecc, ecclen, bitflips_threshold);
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if (ecc_bitflips < 0)
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return ecc_bitflips;
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bitflips_threshold -= ecc_bitflips;
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extraoob_bitflips = nand_check_erased_buf(extraoob, extraooblen,
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bitflips_threshold);
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if (extraoob_bitflips < 0)
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return extraoob_bitflips;
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if (data_bitflips)
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memset(data, 0xff, datalen);
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if (ecc_bitflips)
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memset(ecc, 0xff, ecclen);
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if (extraoob_bitflips)
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memset(extraoob, 0xff, extraooblen);
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return data_bitflips + ecc_bitflips + extraoob_bitflips;
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}
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EXPORT_SYMBOL(nand_check_erased_ecc_chunk);
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/**
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* nand_read_page_raw - [INTERN] read raw page data without ecc
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* @mtd: mtd info structure
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@ -737,6 +737,8 @@ static int mxs_nand_ecc_read_page(struct mtd_info *mtd, struct nand_chip *nand,
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/* Read DMA completed, now do the mark swapping. */
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mxs_nand_swap_block_mark(mtd, nand_info->data_buf, nand_info->oob_buf);
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memcpy(buf, nand_info->data_buf, mtd->writesize);
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/* Loop over status bytes, accumulating ECC status. */
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status = nand_info->oob_buf + mxs_nand_aux_status_offset();
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for (i = 0; i < mxs_nand_ecc_chunk_cnt(mtd->writesize); i++) {
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@ -747,6 +749,44 @@ static int mxs_nand_ecc_read_page(struct mtd_info *mtd, struct nand_chip *nand,
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continue;
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if (status[i] == 0xfe) {
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int flips;
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/*
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* The ECC hardware has an uncorrectable ECC status
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* code in case we have bitflips in an erased page. As
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* nothing was written into this subpage the ECC is
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* obviously wrong and we can not trust it. We assume
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* at this point that we are reading an erased page and
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* try to correct the bitflips in buffer up to
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* ecc_strength bitflips. If this is a page with random
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* data, we exceed this number of bitflips and have a
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* ECC failure. Otherwise we use the corrected buffer.
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*/
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if (i == 0) {
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/* The first block includes metadata */
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flips = nand_check_erased_ecc_chunk(
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buf + i * MXS_NAND_CHUNK_DATA_CHUNK_SIZE,
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MXS_NAND_CHUNK_DATA_CHUNK_SIZE,
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NULL, 0,
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nand_info->oob_buf,
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MXS_NAND_METADATA_SIZE,
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mtd->ecc_strength);
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} else {
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flips = nand_check_erased_ecc_chunk(
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buf + i * MXS_NAND_CHUNK_DATA_CHUNK_SIZE,
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MXS_NAND_CHUNK_DATA_CHUNK_SIZE,
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NULL, 0,
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NULL, 0,
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mtd->ecc_strength);
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}
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if (flips > 0) {
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max_bitflips = max_t(unsigned int,
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max_bitflips, flips);
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corrected += flips;
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continue;
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}
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failed++;
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continue;
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}
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@ -772,8 +812,6 @@ static int mxs_nand_ecc_read_page(struct mtd_info *mtd, struct nand_chip *nand,
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nand->oob_poi[0] = nand_info->oob_buf[0];
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memcpy(buf, nand_info->data_buf, mtd->writesize);
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ret = 0;
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rtn:
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mxs_nand_return_dma_descs(nand_info);
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@ -46,6 +46,11 @@ extern int nand_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len);
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/* unlocks specified locked blocks */
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extern int nand_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len);
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extern int nand_check_erased_ecc_chunk(void *data, int datalen,
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void *ecc, int ecclen,
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void *extraoob, int extraooblen,
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int bitflips_threshold);
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/* The maximum number of NAND chips in an array */
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#define NAND_MAX_CHIPS 8
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