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Date:   Thu, 10 Nov 2022 20:04:45 +0000
From:   Daniel Golle <daniel@makrotopia.org>
To:     Richard Weinberger <richard@nod.at>
Cc:     Jens Axboe <axboe@kernel.dk>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Vignesh Raghavendra <vigneshr@ti.com>,
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        linux-kernel <linux-kernel@vger.kernel.org>,
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Subject: Re: [PATCH v4 4/5] mtd_blkdevs: add option to enable scanning for
 partitions
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On Thu, Nov 10, 2022 at 08:44:53PM +0100, Richard Weinberger wrote:
> ----- Ursprüngliche Mail -----
> > Von: "Daniel Golle" <daniel@makrotopia.org>
> > +
> > +		if (!IS_ENABLED(CONFIG_MTD_BLOCK_PARTITIONS) || mtd_type_is_nand(new->mtd))
> > +			gd->flags |= GENHD_FL_NO_PART;
> 
> I know that NAND should not get used with mtdblock because lack of wearleveling and
> in general too many writes. But what exactly is the rationale to deny part scanning for NAND?

As UBI should be used on NAND, partition scanning should be enabled for
ubiblock devices to have uImage.FIT filesystem subimages mapped by the
partition parser.

If not skipping partition scanning on NAND-backed mtdblock devices the
scanning itself will already trigger multiple warnings which now happen
every time when a NAND-backed mtdblock device is being opened since
commit 96a3295c ("mtdblock: warn if opened on NAND").