[PATCH 5.10 347/717] mtd: spi-nor: ignore errors in spi_nor_unlock_all()

Greg Kroah-Hartman
2020-12-28T14:18:04Z

From: Michael Walle <michael@walle.cc>

[ Upstream commit bdb1a75e4b9df6861ec6a6e3e3997820d3cebabe ]

Just try to unlock the whole SPI-NOR flash array. Don't abort the
probing in case of an error. Justifications:
(1) For some boards, this just works because
spi_nor_write_16bit_sr_and_check() is broken and just checks the
second half of the 16bit. Once that will be fixed, SPI probe will
fail for boards which has hardware-write protected SPI-NOR flashes.
(2) Until now, hardware write-protection was the only viable solution
to use the block protection bits. This is because this very
function spi_nor_unlock_all() will be called unconditionally on
every linux boot. Therefore, this bits only makes sense in
combination with the hardware write-protection. If we would fail
the SPI probe on an error in spi_nor_unlock_all() we'd break
virtually all users of the block protection bits.
(3) We should try hard to keep the MTD working even if the flash might
not be writable/erasable.

Fixes: 3e0930f109e7 ("mtd: spi-nor: Rework the disabling of block write protection")
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20201203162959.29589-3-michael@walle.cc
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/mtd/spi-nor/core.c | 23 +++++++++++++----------
1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index f0ae7a01703a1..61b00d4965475 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -2915,20 +2915,27 @@ static int spi_nor_quad_enable(struct spi_nor *nor)
}

/**
- * spi_nor_unlock_all() - Unlocks the entire flash memory array.
+ * spi_nor_try_unlock_all() - Tries to unlock the entire flash memory array.
* @nor: pointer to a 'struct spi_nor'.
*
* Some SPI NOR flashes are write protected by default after a power-on reset
* cycle, in order to avoid inadvertent writes during power-up. Backward
* compatibility imposes to unlock the entire flash memory array at power-up
* by default.
+ *
+ * Unprotecting the entire flash array will fail for boards which are hardware
+ * write-protected. Thus any errors are ignored.
*/
-static int spi_nor_unlock_all(struct spi_nor *nor)
+static void spi_nor_try_unlock_all(struct spi_nor *nor)
{
- if (nor->flags & SNOR_F_HAS_LOCK)
- return spi_nor_unlock(&nor->mtd, 0, nor->params->size);
+ int ret;

- return 0;
+ if (!(nor->flags & SNOR_F_HAS_LOCK))
+ return;
+
+ ret = spi_nor_unlock(&nor->mtd, 0, nor->params->size);
+ if (ret)
+ dev_dbg(nor->dev, "Failed to unlock the entire flash memory array\n");
}

static int spi_nor_init(struct spi_nor *nor)
@@ -2941,11 +2948,7 @@ static int spi_nor_init(struct spi_nor *nor)
return err;
}

- err = spi_nor_unlock_all(nor);
- if (err) {
- dev_dbg(nor->dev, "Failed to unlock the entire flash memory array\n");
- return err;
- }
+ spi_nor_try_unlock_all(nor);

if (nor->addr_width == 4 && !(nor->flags & SNOR_F_4B_OPCODES)) {
/*
--
2.27.0