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Date:   Thu, 16 Jun 2022 13:35:28 +0300
From:   Mika Westerberg <mika.westerberg@linux.intel.com>
To:     "Oleksandr Ocheretnyi -X (oocheret - GLOBALLOGIC INC at Cisco)" 
        <oocheret@cisco.com>
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Subject: Re: [PATCH v2] mtd: spi-nor: handle unsupported FSR opcodes properly
Message-ID: <YqsHcL5NPcZ4De77@lahna>
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Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo
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Hi,

On Thu, Jun 16, 2022 at 07:40:18AM +0000, Oleksandr Ocheretnyi -X (oocheret - GLOBALLOGIC INC at Cisco) wrote:
>    Hi Mika,
> 
>      > Originally commit 094d3b9 ("mtd: spi-nor: Add USE_FSR flag for
>      n25q*
>      > entries") and following one 8f93826 ("mtd: spi-nor: micron-st:
>      convert
>      > USE_FSR to a manufacturer flag") enabled SPINOR_OP_RDFSR opcode
>      handling
>      > ability, however some controller drivers still cannot handle it
>      properly
>      > in the micron_st_nor_ready() call what breaks some mtd callbacks
>      with
>      > next error logs:
>      >
>      > mtdblock: erase of region [address1, size1] on "BIOS" failed
>      > mtdblock: erase of region [address2, size2] on "BIOS" failed
>      >
>      > The Intel SPI controller does not support low level operations,
>      like
>      > reading the flag status register (FSR). It only exposes a set of
>      high
>      > level operations for software to use. For this reason check the
>      return
>      > value of micron_st_nor_read_fsr() and if the operation was not
>      > supported, use the status register value only. This allows the
>      chip to
>      > work even when attached to Intel SPI controller (there are such
>      systems
>      > out there).
>      >
> 
>    > Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> 
>      I don't think I signed this off.
> 
>    I thought if I take your case (-EOPNOTSUPP) and update it with
>    (-ENOTSUPP) I need to keep
> 
>    your Sighed-off-by: note as well.

That's not how it typically works. People will give their tag explicitly
and then you can add those.

>    > Signed-off-by: Oleksandr Ocheretnyi <oocheret@cisco.com>
>    > Link: [1]https://lore.kernel.org/lkml/YmZUCIE%2FND82BlNh@lahna/
>    > ---
> 
>    What changed between v1 and v2?
> 
>    ​I updated v1 patch taking into account your changes
>    [2]https://lore.kernel.org/linux-mtd/20220506105158.43613-1-mika.wester
>    berg@linux.intel.com to check -EOPNOTSUPP case as well. After I
>    combined both patches I've got v2.

Please put that information after the '---' in the patch.

>    And did you take into consideration the comments I gave?
> 
>    ​If you say about keeping -ENOTSUPP as intel driver errorcode - I took
>    it however doubted to use it here because of note about nfs above.
>    There is no problem to restore previous variant with -ENOTSUPP in intel
>    driver errorcode.

Well we would need to get some feedback from SPI-NOR maintainers. I
would personally keep using ENOTSUPP to be consistent with the rest of
the code in SPI-NOR code (or convert it to use EOPNOTSUPP everywhere)
but it is not up to me ;-)

For Intel driver it is fine to use either (whetever the decision of
SPI-NOR maintainers' is).