mtd-utils: Proper way to handle erasize=0

mtd-utils: Proper way to handle erasize=0

[Fabio Estevam]

Hi,

When using a Microchip 48l640 SRAM (drivers/mtd/devices/mchp48l640.c)
the reported erasesize is 0:

# cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00002000 00000000 "spi0.0"

This causes a division by zero at libmtd.c, as mtd_get_dev_info1() has:

mtd->eb_cnt = mtd->size / mtd->eb_size;

What would be the appropriate way to fix this?

Thanks,

Fabio Estevam

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Re: mtd-utils: Proper way to handle erasize=0

[Richard Weinberger]

----- Ursprüngliche Mail -----
> Von: "festevam" <festevam@gmail.com>
> An: "david oberhollenzer" <david.oberhollenzer@sigma-star.at>, "richard" <richard@nod.at>
> CC: "linux-mtd" <linux-mtd@lists.infradead.org>, "Miquel Raynal" <miquel.raynal@bootlin.com>, "Marek Vasut"
> <marex@denx.de>, "hs" <hs@denx.de>
> Gesendet: Montag, 19. Juli 2021 21:12:26
> Betreff: mtd-utils: Proper way to handle erasize=0

> Hi,
> 
> When using a Microchip 48l640 SRAM (drivers/mtd/devices/mchp48l640.c)
> the reported erasesize is 0:
> 
> # cat /proc/mtd
> dev:    size   erasesize  name
> mtd0: 00002000 00000000 "spi0.0"
> 
> This causes a division by zero at libmtd.c, as mtd_get_dev_info1() has:
> 
> mtd->eb_cnt = mtd->size / mtd->eb_size;
> 
> What would be the appropriate way to fix this?

Didn't this commit address that problem?

commit 54d68799b73e755923def1306b4da607ad45bd60
Author: Chris Packham <chris.packham@alliedtelesis.co.nz>
Date:   Fri Nov 27 13:07:08 2020 +1300

    libmtd: avoid divide by zero
    
    The concept of erase blocks doesn't apply to mtd-ram devices. Such
    devices set MTD_NO_ERASE to indicate this and some report 0 for the
    erase block size. Avoid a divide by zero when calculating the erase
    block count for such devices.
    
    Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
    Acked-by: Richard Weinberger <richard@nod.at>
    Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

Thanks,
//richard

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Re: mtd-utils: Proper way to handle erasize=0

[Fabio Estevam]

Hi Richard,

On Mon, Jul 19, 2021 at 4:36 PM Richard Weinberger <richard@nod.at> wrote:

> Didn't this commit address that problem?

Ah, thanks for pointing that out. This should fix it.

OpenEmbedded is pulling mtd-utils 2.1.2, where this commit is not present.

Maybe it is time to release 2.1.3? :-)

Thanks

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Re: mtd-utils: Proper way to handle erasize=0

[Richard Weinberger]

----- Ursprüngliche Mail -----
> On Mon, Jul 19, 2021 at 4:36 PM Richard Weinberger <richard@nod.at> wrote:
> 
>> Didn't this commit address that problem?
> 
> Ah, thanks for pointing that out. This should fix it.
> 
> OpenEmbedded is pulling mtd-utils 2.1.2, where this commit is not present.
> 
> Maybe it is time to release 2.1.3? :-)

/me eyes David. ;)

Thanks,
//richard

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