Re: [PATCH v2 2/2] mtd: rawnand: Bypass a couple of sanity checks during NAND identification

From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Richard Weinberger <richard@nod.at>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	Tudor Ambarus <tudor.ambarus@linaro.org>,
	Pratyush Yadav <pratyush@kernel.org>,
	Michael Walle <michael@walle.cc>,
	linux-mtd@lists.infradead.org, Alexander Dahl <ada@thorsis.com>,
	Steven Seeger <steven.seeger@flightsystems.net>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	stable@vger.kernel.org
Subject: Re: [PATCH v2 2/2] mtd: rawnand: Bypass a couple of sanity checks during NAND identification
Date: Thu, 16 May 2024 16:45:16 +0200	[thread overview]
Message-ID: <20240516164516.4e5ad1cb@xps-13> (raw)
In-Reply-To: <ZkYPdbspX5tc0WRf@pengutronix.de>

Hi Sascha,

s.hauer@pengutronix.de wrote on Thu, 16 May 2024 15:51:49 +0200:

> On Thu, May 16, 2024 at 03:13:20PM +0200, Miquel Raynal wrote:
> > Early during NAND identification, mtd_info fields have not yet been
> > initialized (namely, writesize and oobsize) and thus cannot be used for
> > sanity checks yet. Of course if there is a misuse of
> > nand_change_read_column_op() so early we won't be warned, but there is
> > anyway no actual check to perform at this stage as we do not yet know
> > the NAND geometry.
> > 
> > So, if the fields are empty, especially mtd->writesize which is *always*
> > set quite rapidly after identification, let's skip the sanity checks.
> > 
> > nand_change_read_column_op() is subject to be used early for ONFI/JEDEC
> > identification in the very unlikely case of:
> > - bitflips appearing in the parameter page,
> > - the controller driver not supporting simple DATA_IN cycles.
> > 
> > As nand_change_read_column_op() uses nand_fill_column_cycles() the logic
> > explaind above also applies in this secondary helper.
> > 
> > Fixes: c27842e7e11f ("mtd: rawnand: onfi: Adapt the parameter page read to constraint controllers")
> > Fixes: daca31765e8b ("mtd: rawnand: jedec: Adapt the parameter page read to constraint controllers")
> > Cc: stable@vger.kernel.org
> > Reported-by: Alexander Dahl <ada@thorsis.com>
> > Closes: https://lore.kernel.org/linux-mtd/20240306-shaky-bunion-d28b65ea97d7@thorsis.com/
> > Reported-by: Steven Seeger <steven.seeger@flightsystems.net>
> > Closes: https://lore.kernel.org/linux-mtd/DM6PR05MB4506554457CF95191A670BDEF7062@DM6PR05MB4506.namprd05.prod.outlook.com/
> > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>  
> 
> With the attached debug patch applied I can confirm that I can now read
> all three ONFI parameter pages successfully using
> nand_change_read_column_op(), so:
> 
> Tested-by: Sascha Hauer <s.hauer@pengutronix.de>

Excellent!

Thanks,
Miquèl

______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/