[PATCH v2] mtd: nand: fix off-by-one read retry mode counting

[Brian Norris]

On Fri, Feb 14, 2014 at 03:58:21PM +0800, Huang Shijie wrote:
> On Wed, Feb 12, 2014 at 05:22:11PM -0800, Brian Norris wrote:
> > A flash may support N read retry voltage threshold modes, numbered 1
> > through N-1 (where mode 0 represents the initial state). However,
> > nand_do_read_ops() tries to use mode 0 through N.
> > 
> > This off-by-one error shows up, for instance, when using nanddump, and
> > we have cycled through available modes:
> > 
> >     nand: setting READ RETRY mode 0
> >     nand: setting READ RETRY mode 1
> >     nand: setting READ RETRY mode 2
> >     nand: setting READ RETRY mode 3
> >     nand: setting READ RETRY mode 4
> >     nand: setting READ RETRY mode 5
> >     nand: setting READ RETRY mode 6
> >     nand: setting READ RETRY mode 7
> >     nand: setting READ RETRY mode 8
> >     libmtd: error!: cannot read 8192 bytes from mtd0 (eraseblock 20, offset 0)
> >             error 22 (Invalid argument)
> >     nanddump: error!: mtd_read
> > 
> > Tested on Micron MT29F64G08CBCBBH1, with 8 retry modes.
> > 
> > Signed-off-by: Brian Norris <computersforpeace at gmail.com>
> > ---
> > v1 -> v2: N modes means we should use modes 0 to N-1, not 0 to N
> > 
> >  drivers/mtd/nand/nand_base.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> > index 9be7842f300e..3cb1cefcd926 100644
> > --- a/drivers/mtd/nand/nand_base.c
> > +++ b/drivers/mtd/nand/nand_base.c
> > @@ -1586,7 +1586,7 @@ read_retry:
> >  			}
> >  
> >  			if (mtd->ecc_stats.failed - ecc_failures) {
> > -				if (retry_mode + 1 <= chip->read_retries) {
> > +				if (retry_mode + 1 < chip->read_retries) {
> >  					retry_mode++;
> >  					ret = nand_setup_read_retry(mtd,
> >  							retry_mode);
> 
> Acked-by: Huang Shijie <b32955 at freescale.com>

Pushed to linux-mtd.git. Will queue up a few other things to send to
Linus in 3.14-rcX.

Brian