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NAND parts can have bitflips in an erased page due to the process technology used. In this case, QCOM NAND controller is not able to identify that page as an erased page. Currently the driver calls nand_check_erased_ecc_chunk() for identifying the erased pages but this won’t work always since the checking is being with ECC engine returned data. In case of bitflips, the ECC engine tries to correct the data and then it generates the uncorrectable error. Now, this data is not equal to original raw data. For erased CW identification, the raw data should be read again from NAND device and this nand_check_erased_ecc_chunk function() should be called for raw data only. Now following logic is being added to identify the erased codeword bitflips. 1. In most of the cases, not all the codewords will have bitflips and only single CW will have bitflips. So, there is no need to read the complete raw page data. The NAND raw read can be scheduled for any CW in page. The NAND controller works on CW basis and it will update the status register after each CW read. Maintain the bitmask for the CW which generated the uncorrectable error. 2. Do raw read for all the CW's which generated the uncorrectable error. 3. Both DATA and OOB need to be checked for number of 0. The top-level API can be called with only data buf or OOB buf so use chip->databuf if data buf is null and chip->oob_poi if OOB buf is null for copying the raw bytes temporarily. 4. For each CW, check the number of 0 in cw_data and usable oob bytes, The bbm and spare (unused) bytes bit flip won’t affect the ECC so don’t check the number of bitflips in this area. Signed-off-by: Abhishek Sahu <absahu@codeaurora.org> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> |
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| onenand | ||
| raw | ||
| spi | ||
| bbt.c | ||
| core.c | ||
| Kconfig | ||
| Makefile | ||