[U-Boot] [PATCH v6 2/8] lpc32xx: mtd: nand: add MLC NAND controller

[Scott Wood <scottwood@freescale.com>]

On Mon, 2015-03-23 at 09:45 +0100, Albert ARIBAUD wrote:
> Bonjour Scott,
> 
> Le Fri, 20 Mar 2015 17:41:11 -0500, Scott Wood
> <scottwood@freescale.com> a ?crit :
> 
> > On Fri, 2015-03-20 at 10:35 +0100, Albert ARIBAUD wrote:
> > > BTW, is there a standard way to ask a NAND chip which page(s) in a bad
> > > block should be checked?
> > 
> > Yes and no:
> > http://lists.infradead.org/pipermail/linux-mtd/2011-November/038419.html
> 
> ... right.
> 
> How about this: the driver expects a driver-specific configuration
> option which tells it which page(s) in a block, and which byte in a
> page's OOB area, should be scanned for bad block markers, and "my"
> board provides a value for said option.

It looks like the common NAND code will set
NAND_BBT_SCANLASTPAGE/NAND_BBT_SCAN2NDPAGE automatically if it sees
certain manufacturer IDs, so I don't think drivers should be setting
them at all (and currently, none do).

That still leaves the question of what to do in SPL.  For simplicity you
could check every page as you do the normal read.

> This leads me to a half-OT question: so those SPL, while too tiny to
> handle non-raw images, still do include the whole common/spl/spl.c

No, there's no room for that.

> > If you want to do this, just put a comment in explaining why you're
> > skipping in that situation.
> 
> Ok -- I will go with the 'option' method then, and add a (lengthy, I'm
> afraid) comment in common/spl/spl.c explaining that skipping the raw
> image handling is required when chainloading from NAND and the NAND
> driver considers totally unreadable sectors bad, in order not to
> confuse a missing image header with a raw image.

Skipping raw wouldn't be needed for all NAND drivers, only those that
aren't guaranteed to halt on a legitimate unrecoverable ECC error.

-Scott