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authorMasahiro Yamada <yamada.masahiro@socionext.com>2017-03-30 09:45:52 +0300
committerBoris Brezillon <boris.brezillon@free-electrons.com>2017-04-25 15:18:34 +0300
commit24715c749b2ff5545f0316e7ad8b65026f9e9612 (patch)
tree911df863e0e9eed6782d75c56032758379390fa9 /Documentation/rtc.txt
parentd29109be2e8d4a102d8304d7b8bb0d6dfe5e1d27 (diff)
downloadlinux-24715c749b2ff5545f0316e7ad8b65026f9e9612.tar.xz
mtd: nand: denali: support HW_ECC_FIXUP capability
Some old versions of the Denali IP (perhaps used only for Intel?) detects ECC errors and provides correct data via a register, but does not touch the transferred data. So, the software must fixup the data in the buffer according to the provided ECC correction information. Newer versions perform ECC correction before transferring the data. No more software intervention is needed. The ECC_ERROR_ADDRESS and ECC_CORRECTION_INFO registers were deprecated. Instead, the number of corrected bit-flips are reported via the ECC_COR_INFO register. When an uncorrectable ECC error happens, a status flag is set to the INTR_STATUS and ECC_COR_INFO registers. As is often the case with this IP, the register view of INTR_STATUS had broken compatibility. For older versions (SW ECC fixup): bit 0: ECC_TRANSACTION_DONE bit 1: ECC_ERR For newer versions (HW ECC fixup): bit 0: ECC_UNCOR_ERR bit 1: Reserved Due to this difference, the irq_mask must be fixed too. The existing handle_ecc() has been renamed to denali_sw_ecc_fixup() for clarification. What is unfortunate with this feature is we can not know the total number of corrected/uncorrected errors in a page. The register ECC_COR_INFO reports the maximum of per-sector bitflips. This is useful for ->read_page return value, but ecc_stats.{corrected,failed} increments may not be precise. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
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