[PATCH v4 0/4] mtd: nand: omap: add support for BCH16_ECC

Pekon Gupta pekon at ti.com
Mon May 19 00:54:38 PDT 2014

As this series touches both linux-mtd and linux-omap (GPMC) sub-systems but in
independent patch-sets, so looping both maintainers. 'Ack' from maintainers would
help in getting this series accepted for 3.16

*changes v3 -> v4*
[PATCH v4 1/4]: minor update in comments
[PATCH v4 2/4]: fixed coding style to keep it generic for big/little endianess
[PATCH v4 3/4]: no change
[PATCH v4 4/4]: use plain english (non linux stuff)

*changes v2 -> v3*
[PATCH v2 3/4] rebased to http://lists.infradead.org/pipermail/linux-mtd/2014-March/052655.html
- no change in other patches

*changes v1 -> v2*
 rebased and cleaned on following versions of pending patches
  (1) [PATCH v8 0/6] mtd: nand: omap: optimized chip->ecc.correct() for H/W ECC schemes

  (2) [PATCH v6 0/4] mtd: nand: omap: optimize chip->ecc.calculate() for H/W ECC schemes

  (3) [PATCH v5 0/4] mtd: nand: omap: optimize chip->ecc.hwctl() for H/W ECC schemes

  (4) [PATCH v6 0/4] mtd: devices: elm: add checks ELM H/W constrains, driver code cleanup
 Tested on Beaglebone-LT(white) NAND cape having NAND Device with
       bus-width=16, block-size=256k, page-size=4k, oob-size=224

*original v1*

With increase in NAND flash densities and shrinking of technology
NAND flash has become more suspectible to multiple bit-flips.
Thus stronger ECC schemes are required for detecting and correcting multiple
simultaneous bit-flips in same NAND page. But stronger ECC schemes have large
ECC syndrome which require more space in OOB/Spare.

This patch add support for BCH16 ecc-scheme on OMAP NAND driver:
(a) BCH16 ecc-scheme can correct 16 bit-flips per 512Bytes of data.
(b) BCH16 ecc-scheme generates 26-bytes of ECC syndrome / 512B.

Due to (b) this scheme can only be used with NAND devices which have enough
OOB to satisfy following equation:
OOBsize per page >= 26 * (page-size / 512)

Pekon Gupta (4):
  mtd: nand: omap: add support for BCH16_ECC - GPMC driver updates
  mtd: nand: omap: add support for BCH16_ECC - ELM driver updates
  mtd: nand: omap: add support for BCH16_ECC - NAND driver updates
  mtd: nand: omap: Documentation: How to select correct ECC scheme for
    your device ?

 .../devicetree/bindings/mtd/gpmc-nand.txt          | 45 +++++++++++
 arch/arm/mach-omap2/gpmc.c                         | 15 ++++
 drivers/mtd/devices/elm.c                          | 36 +++++++++
 drivers/mtd/nand/omap2.c                           | 94 ++++++++++++++++++++++
 include/linux/platform_data/elm.h                  |  3 +-
 include/linux/platform_data/mtd-nand-omap2.h       |  5 ++
 6 files changed, 197 insertions(+), 1 deletion(-)


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