[U-Boot] [PATCHv2 CFI flash]: Workaround for Numonyx Axcell P33/P30 256-Mbit 65nm bug

[Philippe De Muyter <phdm@macqel.be>]

Hello Joakim,

On Mon, Aug 09, 2010 at 10:32:25AM +0200, Joakim Tjernlund wrote:
> >
> > Dear Stefan,
> >
> > In message <20100623131040.GA23209@frolo.macqel> Philippe De Muyter wrote:
> > > Hello Wolfgang & list,
> > >
> > > This is a revised patch, with comments and indentation fixed, I hope.
> > >
> > > I have "ported" U-boot to a in house made board with Numonyx Axcell P33/P30
> > > 256-Mbit 65nm flash chips.
> > >
> > > After some time :( searching for bugs in our board or soft, we have
> > > discovered that those chips have a small but annoying bug, documented in
> > > "Numonyx Axcell P33/P30 256-Mbit Specification Update"
> > >
> > > It states :
> > > When customer uses [...] block unlock, the block lock status might be
> > > altered inadvertently. Lock status might be set to either 01h or 03h
> > > unexpectedly (00h as expected data), which leads to program/erase failure
> > > on certain blocks.
> > >
> > > A working workaround is given, which I have applied and tested with success.
> > >
> > > Signed-off-by: Philippe De Muyter <phdm@macqel.be>
> > >
> > > ---
> > >  drivers/mtd/cfi_flash.c |   27 ++++++++++++++++++++-------
> > >  1 files changed, 20 insertions(+), 7 deletions(-)
> >
> > I didn't see comments from you?
> >
> > Best regards,
> >
> > Wolfgang Denk
> 
> Doesn't the Linux kernel need the same fix? Would be great if
> you(Philippe) could provide one. I too have such chips but I have
> never seen this problem so I guess I have been lucky so far :)
> 
>       Jocke

I use linux on those boards, of course, so I also thought that I'd need
to fix linux, but I didn't have to.  On the boards I had, the bug was
easily repeatable with u-boot or the bdm-tools's bdm-based flash programmer
I used.  The same blocks always gave the same error, while other blocks
always worked perfectly.  From linux, I tested with eraseall from mtd-utils
also on the bad blocks and I never had any problem, so linux probably
already does the erase sequence the way numonyx testers do it.  The key
point is that the CFI unlock command sequence must come just before the
CFI erase command sequence, not long before.

Philippe