From: Michael Walle <michael@walle.cc>
To: Tudor.Ambarus@microchip.com
Cc: linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org,
miquel.raynal@bootlin.com, richard@nod.at, vigneshr@ti.com,
boris.brezillon@collabora.com
Subject: Re: [PATCH v6 5/5] mtd: spi-nor: keep lock bits if they are non-volatile
Date: Wed, 02 Dec 2020 12:25:49 +0100 [thread overview]
Message-ID: <fe04f234584c2f459e865955b0d09303@walle.cc> (raw)
In-Reply-To: <8e0a6a20-2779-9397-eedf-02518b4a0e5a@microchip.com>
Am 2020-12-02 12:10, schrieb Tudor.Ambarus@microchip.com:
> On 11/30/20 4:38 PM, Michael Walle wrote:
[..]
>>>> + * indicated by SNOR_F_WP_IS_VOLATILE.
>>>> + */
>>>> + if (IS_ENABLED(CONFIG_MTD_SPI_NOR_WP_DISABLE) ||
>>>> + (IS_ENABLED(CONFIG_MTD_SPI_NOR_WP_DISABLE_ON_VOLATILE)
>>>> &&
>>>> + nor->flags & SNOR_F_WP_IS_VOLATILE)) {
>>>> + err = spi_nor_unlock_all(nor);
>>>> + if (err) {
>>>> + dev_err(nor->dev, "Failed to unlock the
>>>> entire
>>>> flash memory array\n");
>>>
>>> dev_dbg for low level info
>>
>> Is this low level info or an actual error? Which raises the question:
>> should spi_nor_unlock_all() in case SWRD couldn't be cleared and thus
>> should all the spi_nor_init fail of this? Or should it rather be a
>
> yes, it should, because the flash will not work as expected/requested.
One counterargument: take our sl28 board, it has a hardware
write-protected
SPI flash. It actually works right now because the write_sr_and_check()
doesn't work as intended and doesn't check what is written. So if you'd
fix that (and these changes would be backported to the stable trees),
you'd
basically break spi-nor on these boards. And this _must_ be the case for
all boards which are actually using (hard- or sofware) write-protection.
That is the only way write-protection makes sense prior to this patch
series. Because linux will happily unlock every flash on startup.
Therefore,
the hardware write protection is the only measure against this.
-michael
next prev parent reply other threads:[~2020-12-02 11:26 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-26 20:26 [PATCH v6 0/5] mtd: spi-nor: keep lock bits if they are non-volatile Michael Walle
2020-11-26 20:26 ` [PATCH v6 1/5] mtd: spi-nor: atmel: remove global protection flag Michael Walle
2020-11-26 20:26 ` [PATCH v6 2/5] mtd: spi-nor: sst: " Michael Walle
2020-11-26 20:26 ` [PATCH v6 3/5] mtd: spi-nor: intel: " Michael Walle
2020-11-27 9:07 ` Tudor.Ambarus
2020-11-26 20:26 ` [PATCH v6 4/5] mtd: spi-nor: atmel: Fix unlock_all() for AT25FS010/040 Michael Walle
2020-11-28 8:25 ` Tudor.Ambarus
2020-11-30 14:16 ` Michael Walle
2020-12-02 10:32 ` Tudor.Ambarus
2020-11-26 20:26 ` [PATCH v6 5/5] mtd: spi-nor: keep lock bits if they are non-volatile Michael Walle
2020-11-28 10:17 ` Tudor.Ambarus
2020-11-30 14:38 ` Michael Walle
2020-12-02 11:10 ` Tudor.Ambarus
2020-12-02 11:25 ` Michael Walle [this message]
2020-12-02 14:09 ` Tudor.Ambarus
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