Re: [PATCH v2] mtd: rawnand: Do not check FAIL bit when executing a SET_FEATURES op

[Miquel Raynal <miquel.raynal@bootlin.com>]

Hi Boris,

On Fri, 11 May 2018 14:44:07 +0200, Boris Brezillon
<boris.brezillon@bootlin.com> wrote:

> The ONFI spec clearly says that FAIL bit is only valid for PROGRAM,
> ERASE and READ-with-on-die-ECC operations, and should be ignored
> otherwise.
> 
> It seems that checking it after sending a SET_FEATURES is a bad idea
> because a previous READ, PROGRAM or ERASE op may have failed, and
> depending on the implementation, the FAIL bit is not cleared until a
> new READ, PROGRAM or ERASE is started.
> 
> This leads to ->set_features() returning -EIO while it actually worked,
> which can sometimes stop a batch of READ/PROGRAM ops.
> 
> Note that we only fix the ->exec_op() path here, because some drivers
> are abusing the NAND_STATUS_FAIL flag in their ->waitfunc()
> implementation to propagate other kind of errors, like
> wait-ready-timeout or controller-related errors. Let's not try to fix
> those drivers since they worked fine so far.
> 
> Fixes: 8878b126df76 ("mtd: nand: add ->exec_op() implementation")
> Cc: stable@vger.kernel.org
> Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
> ---

So we have no real way to know if a SET_FEATURES actually succeeded.
I checked the ONFI spec and could not find anything. A GET_FEATURES
will do the trick though (when supported).

Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>