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From:   Pintu Agarwal <pintu.ping@gmail.com>
Date:   Wed, 12 Jul 2023 19:29:39 +0530
Message-ID: <CAOuPNLizjBp_8ceKq=RLznXdsHD-+N55RoPh_D7_Mpkg7M-BwQ@mail.gmail.com>
Subject: MTD: Lots of mtdblock warnings on bootup logs
To:     open list <linux-kernel@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        linux-mtd <linux-mtd@lists.infradead.org>,
        linux-fsdevel@kvack.org, ezequiel@collabora.com,
        Miquel Raynal <miquel.raynal@bootlin.com>, bjorn@mork.no
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Hi,

We are getting below warning messages in dmesg logs on a NAND device
for every raw partition.
Kernel: 5.15 ; arm64 ; NAND + ubi + squashfs
We have some RAW partitions and one UBI partition (with ubifs/squashfs volumes).

We are seeing large numbers of these logs on the serial console that
impact the boot time.
[....]
[    9.667240][    T9] Creating 58 MTD partitions on "1c98000.nand":
[....]
[   39.975707][  T519] mtdblock: MTD device 'uefi_a' is NAND, please
consider using UBI block devices instead.
[   39.975707][  T519] mtdblock: MTD device 'uefi_b' is NAND, please
consider using UBI block devices instead.
[....]

This was added as part of this commit:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/drivers/mtd/mtdblock.c?h=v5.15.120&id=f41c9418c5898c01634675150696da290fb86796
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/drivers/mtd/mtdblock.c?h=v5.15.120&id=e07403a8c6be01857ff75060b2df9a1aa8320fe5

I think this warning was decided after my last year's discussion about
mtdblock vs ubiblock for squashfs.

But these are raw NAND partitions and not mounted by us.

What is the exact meaning of these warnings ?

We have both these configs enabled:
CONFIG_MTD_BLOCK=y
CONFIG_MTD_UBI_BLOCK=y

Through this warning, are we telling that only one of the above config
should be enabled ?
And the recommendation is to use ubi_block and disable mtd_block ?

We are already using ubiblock for mounting squashfs volumes.
But how to get rid of these warnings for raw NAND partitions ?

Is there a way to avoid or we are missing something which we are not aware of?


Thanks,
Pintu