One of the limitations of the NAND devices is the method used to read NAND flash memory may cause bit-flips on the surrounding cells and result in uncorrectable ECC errors. This is known as the read disturb or data retention. Today’s Linux NAND drivers implementation doesn’t address the read disturb and the data retention limitations of the NAND devices. To date these issues could be overlooked since the possibility of their occurrence in today’s NAND devices is very low. With the evolution of NAND devices and the requirement for a “long life” NAND flash, read disturb and data retention can no longer be ignored otherwise there will be data loss over time. The following patch set implements handling of Read-disturb and Data retention by the UBI layer. Changes from V1: - Documentation file was added in the first patch that describes the design in general. All other patches were unchanged and resent just for reference. Still working on comments from Richard on fastmap layout. All comments that were made for V1 will be addressed in the next patch set. This version is just for the addition of the documentation file. Tanya Brokhman (5): mtd: ubi: Read disturb infrastructure mtd: ubi: Fill read disturb statistics mtd: ubi: Make in_wl_tree function public mtd: ubi: Read threshold verification mtd: ubi: Add sysfs entry to force all pebs' scan Documentation/mtd/ubi/ubi-read-disturb.txt | 145 ++++++++++++++++ drivers/mtd/ubi/attach.c | 137 +++++++++++---- drivers/mtd/ubi/build.c | 81 +++++++++ drivers/mtd/ubi/debug.c | 11 ++ drivers/mtd/ubi/eba.c | 7 +- drivers/mtd/ubi/fastmap.c | 132 +++++++++++--- drivers/mtd/ubi/io.c | 28 +++ drivers/mtd/ubi/ubi-media.h | 32 +++- drivers/mtd/ubi/ubi.h | 62 ++++++- drivers/mtd/ubi/vtbl.c | 6 +- drivers/mtd/ubi/wl.c | 270 +++++++++++++++++++++++++++-- 11 files changed, 835 insertions(+), 76 deletions(-) create mode 100644 Documentation/mtd/ubi/ubi-read-disturb.txt -- Qualcomm Israel, on behalf of Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
