NAND ECC and OOB usage

Phil Thompson phil at
Tue Feb 18 10:53:41 EST 2003

On Tuesday 18 February 2003 4:45 pm, Thomas Gleixner wrote:
> On Tuesday 18 February 2003 16:17, Phil Thompson wrote:
> > > You don't need that, as the filesystem forces layout selection itself.
> >
> > So why hardcode it in autcpu12.c? If it's useful to be able to hardcode
> > the selector then it must also be useful to parameterise it in mtdparts.
> >
> > But maybe it isn't useful to hardcode it either.
> >
> > As I understand it, the only point of including the selector in struct
> > mtd_info is to provide an appropriate default when using user space tools
> > that aren't aware of OOB data and ECC. In other words so that you can
> > do... dd if=jffs2_image of=/dev/mtd1
> You can use write and read from userspace, e.g. to burn an image on the
> partition. You still have to deal with bad blocks, but you can use non NAND
> specific functions for read and write.


> > ...and have the OOB data initialised properly. However, because you have
> > to deal with potential bad blocks, you shouldn't be using user space
> > tools that aren't aware of OOB data. You should be using something like
> > your enhanced nandwrite which is going to use the MEMSETOOBSEL ioctl to
> > explicitly set the selector correctly anyway.
> > In other words, I can't see the point in having the selector in struct
> > mtd_partition at all.
> 1. It's the only way to set the dfault for a partition

In which case my original point is valid - you should also be able to set the 
default through mtdparts.


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