Re: [PATCH] mtd: nand: default bitflip-reporting threshold to 75% of correction strength

[Brian Norris <computersforpeace@gmail.com>]

On Mon, Jan 12, 2015 at 12:51:29PM -0800, Brian Norris wrote:
> The MTD API reports -EUCLEAN only if the maximum number of bitflips
> found in any ECC block exceeds a certain threshold. This is done to
> avoid excessive -EUCLEAN reports to MTD users, which may induce
> additional scrubbing of data, even when the ECC algorithm in use is
> perfectly capable of handling the bitflips.
> 
> This threshold can be controlled by user-space (via sysfs), to allow
> users to determine what they are willing to tolerate in their
> application. But it still helps to have sane defaults.
> 
> In recent discussion [1], it was pointed out that our default threshold
> is equal to the correction strength. That means that we won't actually
> report any -EUCLEAN (i.e., "bitflips were corrected") errors until there
> are almost too many to handle. It was determined that 3/4 of the
> correction strength is probably a better default.
> 
> [1] http://lists.infradead.org/pipermail/linux-mtd/2015-January/057259.html
> 
> Signed-off-by: Brian Norris <computersforpeace@gmail.com>

Pushed to l2-mtd.git.

Brian