[PATCH] mtd: rawnand: micron: Fix support for on-die ECC

[Boris Brezillon]

On Tue, 8 May 2018 23:12:59 +0200
Boris Brezillon <boris.brezillon at bootlin.com> wrote:

> On Fri, 4 May 2018 11:58:35 +0200
> Miquel Raynal <miquel.raynal at bootlin.com> wrote:
> 
> > Hi Boris,
> > 
> > On Thu,  3 May 2018 09:49:08 +0200, Boris Brezillon
> > <boris.brezillon at bootlin.com> wrote:
> >   
> > > It looks like the NAND_STATUS_FAIL bit is sticky after an ECC failure,
> > > which leads all READ operations following the failing one to report
> > > an ECC failure. Reset the chip to clear the NAND_STATUS_FAIL bit.
> > > 
> > > Note that this behavior is not document in the datasheet, but resetting
> > > the chip is the only solution we found to fix the problem.
> > > 
> > > Fixes: 9748e1d87573 ("mtd: nand: add support for Micron on-die ECC")
> > > Cc: <stable at vger.kernel.org>
> > > Signed-off-by: Boris Brezillon <boris.brezillon at bootlin.com>
> > > Cc: Thomas Petazzoni <thomas.petazzoni at bootlin.com>
> > > Cc: Bean Huo <beanhuo at micron.com>
> > > Cc: Peter Pan <peterpandong at micron.com>
> > > ---    
> > 
> > Reviewed-by: Miquel Raynal <miquel.raynal at bootlin.com>  
> 
> Queued to mtd/master.

I'm dropping this patch because I'm no longer sure this is the correct
way to fix bug. It seems that nand_set_features_op() is checking the
FAIL bit while the ONFI spec clearly says that FAIL bit is only valid
after a PROGRAM, ERASE or READ-with-on-die-ECC-enabled op. That might
explain why ->set_features() fails with -EIO after an ECC failure
(apparently Micron only clears the FAIL bit when launching a PROGRAM,
ERASE or READ-with-on-die-ECC-enabled op, not on a SET_FEATURES op).