Skip to content
  1. Jan 14, 2014
    • Brian Norris's avatar
      mtd: nand: add generic READ RETRY support · ba84fb59
      Brian Norris authored
      
      
      Modern MLC (and even SLC?) NAND can experience a large number of
      bitflips (beyond the recommended correctability capacity) due to drifts
      in the voltage threshold (Vt). These bitflips can cause ECC errors to
      occur well within the expected lifetime of the flash. To account for
      this, some manufacturers provide a mechanism for shifting the Vt
      threshold after a corrupted read.
      
      The generic pattern seems to be that a particular flash has N read retry
      modes (where N = 0, traditionally), and after an ECC failure, the host
      should reconfigure the flash to use the next available mode, then retry
      the read operation. This process repeats until all bitfips can be
      corrected or until the host has tried all available retry modes.
      
      This patch adds the infrastructure support for a
      vendor-specific/flash-specific callback, used for setting the read-retry
      mode (i.e., voltage threshold).
      
      For now, this patch always returns the flash to mode 0 (the default
      mode) after a successful read-retry, according to the flowchart found in
      Micron's datasheets. This may need to change in the future if it is
      determined that eventually, mode 0 is insufficient for the majority of
      the flash cells (and so for performance reasons, we should leave the
      flash in mode 1, 2, etc.).
      
      Signed-off-by: default avatarBrian Norris <computersforpeace@gmail.com>
      Acked-by: default avatarHuang Shijie <b32955@freescale.com>
      ba84fb59
    • Brian Norris's avatar
    • Brian Norris's avatar
      mtd: nand: localize ECC failures per page · b72f3dfb
      Brian Norris authored
      
      
      ECC failures can be tracked at the page level, not the do_read_ops level
      (i.e., a potentially multi-page transaction).
      
      This helps prepare for READ RETRY support.
      
      Signed-off-by: default avatarBrian Norris <computersforpeace@gmail.com>
      Acked-by: default avatarHuang Shijie <b32955@freescale.com>
      b72f3dfb
  2. Jan 13, 2014
  3. Jan 12, 2014
  4. Jan 10, 2014
  5. Jan 08, 2014
  6. Jan 04, 2014