[U-Boot] [U-Boot, v2, 2/3] mtd: nand: omap: add support for BCH16_ECC - NAND driver updates

[Gupta, Pekon]

> From: Scott Wood [mailto:scottwood at freescale.com]
> > On Tue, Sep 10, 2013 at 12:55:07PM +0530, pekon gupta wrote:
> > With increase in NAND flash densities occurence of bit-flips has increased.
> > Thus stronger ECC schemes are required for detecting and correcting
> multiple
> > simultaneous bit-flips in same NAND page. But stronger ECC schemes have
> large
> > ECC syndrome which require more space in OOB/Spare.
> > This patch add support for BCH16_ECC:
> > (a) BCH16_ECC can correct 16 bit-flips per 512Bytes of data.
> > (b) BCH16_ECC generates 26-bytes of ECC syndrome / 512B.
> >
> > Due to (b) this scheme can only be used with NAND devices which have
> enough
> > OOB to satisfy following equation:
> > OOBsize per page >= 26 * (page-size / 512)
> >
> > Signed-off-by: Pekon Gupta <pekon at ti.com>
> >
> > ---
> > arch/arm/include/asm/arch-am33xx/cpu.h       | 15 ++++-
> >  arch/arm/include/asm/arch-am33xx/omap_gpmc.h |  4 +-
> >  drivers/mtd/nand/omap_gpmc.c                 | 87
> +++++++++++++++++++++++-----
> >  include/mtd/mtd-abi.h                        |  3 +-
> >  4 files changed, 90 insertions(+), 19 deletions(-)
> 
> This doesn't apply cleanly.
> 
This one is on top of previous patch series like..
[Part 1] http://lists.denx.de/pipermail/u-boot/2013-November/167393.html
[Part 2] http://lists.denx.de/pipermail/u-boot/2013-November/167445.html

So once the above series are cleaned and accepted. I'll rebase and re-send this
series for BCH16 ecc-scheme again..


> > diff --git a/arch/arm/include/asm/arch-am33xx/cpu.h
> b/arch/arm/include/asm/arch-am33xx/cpu.h
> > index 10b56e0..1de92e6 100644
> > --- a/arch/arm/include/asm/arch-am33xx/cpu.h
> > +++ b/arch/arm/include/asm/arch-am33xx/cpu.h
> > @@ -63,7 +63,16 @@ struct gpmc_cs {
> >  };
> >
> >  struct bch_res_0_3 {
> > -	u32 bch_result_x[4];
> > +	u32 bch_result0;
> > +	u32 bch_result1;
> > +	u32 bch_result2;
> > +	u32 bch_result3;
> > +};
> 
> Is this really an improvement?
> 
Good for readability to match it to actual IP spec.. 
Each of bch_resultx map to individual 32-bit registers named accordingly
in IP spec.


> It would also be nice if headers for things in drivers/mtd/nand weren't
> in arch.
> 
I agree.. but I would take that separately, as I need to test all other
platforms also for this change .. (like am335x, am43xx, omap3.. )


with regards, pekon