information on accessing nand

[Ian Lepore]

On Wed, 2016-04-06 at 21:41 +0100, Craig Butler wrote:
> Hello List
> 
> Is there a HOWTO or some instructions/black magic for adding new
> definitions and drivers for accessing currently unsupported nand ??
> 
> So far I *think* I need to;
>  - define the nand in the board dts definitions 
>  - code a nfc_ (omap2??) driver
>  - set kernel configs with option nandfs and WITH_NAND="YES"
>  - cross fingers
> 
> Have I missed anything ?
> 
> Kind Regards
> 

You should be aware before you get too far into this that there is lots
of stuff in freebsd related to nand, and most of it doesn't work.  The
driver framework is completely tied to 1-bit hamming code ECC, which is
only used by ancient small chips, nothing modern.  If you get past that
(say, by using chips with builtin hardware ECC that appear to just
never get errors), you quickly discover that the nandfs code is slow
and buggy.  Slow like it can lock up the system for seconds at a time. 
 Buggy like it corrupts data and there's no way to recover.

-- Ian