[RFC][PATCH][JFFS2] JFFS2 support for NOP 1

[Kyungmin Park]

On Nov 28, 2007 11:47 AM, Jörn Engel <joern at logfs.org> wrote:
> On Wed, 28 November 2007 11:08:30 +0900, Kyungmin Park wrote:
> >
> > sub-page: possible write size(?)
> > MTD usually write data with 'page size' (1KiB, 2KiB, and 4KiB) but
> > some upper layer such as UBI can write it with 'sub-page size (sector
> > size)'.
> >
> > Number Of Program (NOP): How many times flash can be programed.
> > In general SLC NAND has 4 but this value will be smaller as the
> > technology is advanced and MLC NAND has 1.
> >
> > The problem is that current JFFS2 implementation uses the NOP 2, data
> > area and oob area in NAND case. It breaks the NOP 1 limitation in MLC
> > case.
> >
> > If the description is wrong, please let me know.
>
> Sounds plausible.  And reading up on the subpage code I start to doubt
> its robustness wrt. newer SLC flashes as well.  If the NOP is lower than
> the number of ECC steps, trouble is brewing.
>
> But back to your original patch, you want JFFS2 to behave on MLC flashes
> just as it already behaves on Sibley and those dreaded STMicro NORs.
> And I claim that you should not only reach identical behaviour, but also
> share the same code.  There is no point in having two sets of "special"
> initializations with the exact same effect.
>
> Maybe add a flag MTD_OOB_WRITEABLE (or some better name) to SLC flashes
> and have the nand initializations in JFFS2 depend on those.  Without
> this flag, the nor_wbuf_* code is called.  "nor_wbuf" could use a better
> name as well, since it extends to more than just NOR flash.
>

Okay, I will add the MTD_OOB_WRITABLE as NOR.

Are there more opinions or comments?
If not, I will send the updated patch.

Thank you,
Kyungmin Park