[PATCH 3/4] mtd: nand: support Micron READ RETRY

[Huang Shijie]

On Thu, Dec 05, 2013 at 12:58:38PM -0800, Brian Norris wrote:
> Caught a simple bug when testing with a non-READ_RETRY NAND. See below.
> 
> On Thu, Dec 05, 2013 at 12:19:59PM -0800, Brian Norris wrote:
> ...
> > One thing I'm not sure about: do all relevant (i.e., ONFI-capable) NAND drivers
> > support SET_FEATURES properly? If not, then it's possible that this could break
> > nand_do_read_ops for such drivers. Not sure what the best method of handling
> > that would be.
> ...
> > --- a/drivers/mtd/nand/nand_base.c
> > +++ b/drivers/mtd/nand/nand_base.c
> ...
> > @@ -1512,8 +1535,27 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
> >  					nand_wait_ready(mtd);
> >  			}
> >  
> > -			if (mtd->ecc_stats.failed - ecc_failures)
> > -				ecc_fail = true;
> > +			if (mtd->ecc_stats.failed - ecc_failures) {
> > +				retry_mode++;
> 
> This increment shouldn't be done for all ECC failures, but only for
> failures where there are remaining read-retry modes (i.e., flash that
> support read retry).
> 
> > +				if (retry_mode < chip->read_retries) {
> > +					pr_debug("ECC error; performing READ RETRY %d\n",
> > +							retry_mode);
> > +
> > +					ret = nand_set_read_retry(mtd,
> > +							retry_mode);
> > +					if (ret < 0)
> > +						break;
> > +
> > +					/* Reset failures */
> > +					mtd->ecc_stats.failed = ecc_failures;
> > +					continue;
> > +				} else {
> > +					/* No more retry modes; real failure */
> > +					ecc_fail = true;
> > +				}
> > +			}
> > +
> > +			buf += bytes;
> >  		} else {
> >  			memcpy(buf, chip->buffers->databuf + col, bytes);
> >  			buf += bytes;
> 
> I'll send a v2 with the following extra diff:

I am glad you begin to add the read-retry support.

I ever planned to send out my read-retry patch set (which has been queued
in my hand for half of year) after I finish the
spi nor framework. 

I can not wait to review your V2 patch.

thanks
Huang Shijie