Linux-mtd Archive on
 help / color / Atom feed
From: <>
To: <>, <>
Subject: Re: [BUG]: spi-nor: spi_nor_init() fails when SR locked
Date: Tue, 21 Jul 2020 09:37:02 +0000
Message-ID: <> (raw)
In-Reply-To: <>

Hi, David,

On 7/20/20 9:13 PM, David Clear wrote:
> Hi Tudor,
> I'm seeing a change of behavior in spi-nor/next vs. my older 4.14
> kernel w.r.t. how SR lock is working.
> In my system with a Micron mt25qu02g, I'm using the hardware WP# to
> lock the SR.  When hardware write-protect is on, at the next reboot
> the kernel rejects the flash as it cannot unlock the whole device.
> I traced the problem to spi_nor_write_sr1_and_check(), which is
> writing to the SR and reading back a different value (as the locked SR
> bits are immutable).
> Call trace:
>  spi_nor_write_sr1_and_check+0x68/0x70
>  spi_nor_write_sr_and_check+0x34/0xd0
>  spi_nor_sr_unlock+0x108/0x230
>  spi_nor_unlock+0x54/0x80  (via spi_nor_unlock_all())
>  spi_nor_init+0x94/0x100
> spi_nor_write_sr1_and_check() is returning -EIO here:
>         if (nor->bouncebuf[0] != sr1) {
>                 dev_dbg(nor->dev, "SR1: read back test failed\n");
>                 BUG();
>                 return -EIO;
>         }
> In my specific case Linux doesn't have (and cannot be given, for
> product security reasons) control over the WP#.  In any case, I don't
> think a write-protected flash should be rejected here.
> Can you suggest how we might proceed?  The way WP# is used is
> board-specific so perhaps a device-tree property of some sort in the
> flash device node can inform the code to do or not do the
> spi_nor_unlock_all()?
> I can take a look at putting a patch together if you suggest an
> acceptable mechanism.

Thanks for the detailed report. I'll have to study this a bit, I'll get
back to you in few days/one week. We tackled the unlock_all stuff in
the past, Michael did a patch, I'll check how that fits here.


Linux MTD discussion mailing list

  reply index

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-20 18:13 David Clear
2020-07-21  9:37 ` Tudor.Ambarus [this message]
2020-07-21 17:02   ` David Clear

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-mtd Archive on

Archives are clonable:
	git clone --mirror linux-mtd/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-mtd linux-mtd/ \
	public-inbox-index linux-mtd

Example config snippet for mirrors

Newsgroup available over NNTP:

AGPL code for this site: git clone