[PATCH 1/2] Revert "mtd: spi-nor: Disable the flash quad mode in spi_nor_restore()"

[PATCH 1/2] Revert "mtd: spi-nor: Disable the flash quad mode in spi_nor_restore()"

[Yicong Yang]

Previous patch intends to restore the flash's QE bit when removed/shutdown,
but may have some problems and break the flash:

- for those originally in Quad mode, this patch will clear the QE bit
  when unloaded the flash, which is incorrect.
- even with above problem solved, it may still break the flash as some
  flash's QE bit is non-volatile and lots of set/reset will wear out
  the bit.
- the restore method cannot be proved to be valid as if a hard
  reset or accident crash happened, the spi_nor_restore() won't be
  performed the the QE bit will not be restored as we expected to.

So let's revert it to fix this. The discussion can be found at [1].

This reverts commit cc59e6bb6cd69d3347c06ccce088c5c6052e041e.

[1] https://lore.kernel.org/linux-mtd/CAO8h3eFLVLRmw7u+rurKsg7=Nh2q-HVq-HgVXig8gf5Dffk8MA@mail.gmail.com/
Reported-by: Matthias Weisser <m.weisser.m@gmail.com>
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Suggested-by: Vignesh Raghavendra <vigneshr@ti.com>
---
 drivers/mtd/spi-nor/core.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index 65eff4c..ab8f554 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -3000,8 +3000,6 @@ void spi_nor_restore(struct spi_nor *nor)
 	if (nor->addr_width == 4 && !(nor->flags & SNOR_F_4B_OPCODES) &&
 	    nor->flags & SNOR_F_BROKEN_RESET)
 		nor->params->set_4byte_addr_mode(nor, false);
-
-	spi_nor_quad_enable(nor, false);
 }
 EXPORT_SYMBOL_GPL(spi_nor_restore);
 
-- 
2.8.1


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[PATCH 2/2] Revert "mtd: spi-nor: Add capability to disable flash quad mode"

[Yicong Yang]

As the only user has been removed in previous patch, let's revert
this one together.

This reverts commit be192209d5a33c912caa4a05d6f92b89328d8db8.

Reported-by: Matthias Weisser <m.weisser.m@gmail.com>
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Suggested-by: Vignesh Raghavendra <vigneshr@ti.com>
---
 drivers/mtd/spi-nor/core.c | 55 ++++++++++++++++------------------------------
 drivers/mtd/spi-nor/core.h | 10 ++++-----
 2 files changed, 24 insertions(+), 41 deletions(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index ab8f554..0369d98 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -1907,16 +1907,15 @@ static int spi_nor_is_locked(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 }
 
 /**
- * spi_nor_sr1_bit6_quad_enable() - Set/Unset the Quad Enable BIT(6) in the
- *                                  Status Register 1.
+ * spi_nor_sr1_bit6_quad_enable() - Set the Quad Enable BIT(6) in the Status
+ * Register 1.
  * @nor:	pointer to a 'struct spi_nor'
- * @enable:	true to enable Quad mode, false to disable Quad mode.
  *
  * Bit 6 of the Status Register 1 is the QE bit for Macronix like QSPI memories.
  *
  * Return: 0 on success, -errno otherwise.
  */
-int spi_nor_sr1_bit6_quad_enable(struct spi_nor *nor, bool enable)
+int spi_nor_sr1_bit6_quad_enable(struct spi_nor *nor)
 {
 	int ret;
 
@@ -1924,56 +1923,45 @@ int spi_nor_sr1_bit6_quad_enable(struct spi_nor *nor, bool enable)
 	if (ret)
 		return ret;
 
-	if ((enable && (nor->bouncebuf[0] & SR1_QUAD_EN_BIT6)) ||
-	    (!enable && !(nor->bouncebuf[0] & SR1_QUAD_EN_BIT6)))
+	if (nor->bouncebuf[0] & SR1_QUAD_EN_BIT6)
 		return 0;
 
-	if (enable)
-		nor->bouncebuf[0] |= SR1_QUAD_EN_BIT6;
-	else
-		nor->bouncebuf[0] &= ~SR1_QUAD_EN_BIT6;
+	nor->bouncebuf[0] |= SR1_QUAD_EN_BIT6;
 
 	return spi_nor_write_sr1_and_check(nor, nor->bouncebuf[0]);
 }
 
 /**
- * spi_nor_sr2_bit1_quad_enable() - set/unset the Quad Enable BIT(1) in the
- *                                  Status Register 2.
+ * spi_nor_sr2_bit1_quad_enable() - set the Quad Enable BIT(1) in the Status
+ * Register 2.
  * @nor:       pointer to a 'struct spi_nor'.
- * @enable:	true to enable Quad mode, false to disable Quad mode.
  *
  * Bit 1 of the Status Register 2 is the QE bit for Spansion like QSPI memories.
  *
  * Return: 0 on success, -errno otherwise.
  */
-int spi_nor_sr2_bit1_quad_enable(struct spi_nor *nor, bool enable)
+int spi_nor_sr2_bit1_quad_enable(struct spi_nor *nor)
 {
 	int ret;
 
 	if (nor->flags & SNOR_F_NO_READ_CR)
-		return spi_nor_write_16bit_cr_and_check(nor,
-						enable ? SR2_QUAD_EN_BIT1 : 0);
+		return spi_nor_write_16bit_cr_and_check(nor, SR2_QUAD_EN_BIT1);
 
 	ret = spi_nor_read_cr(nor, nor->bouncebuf);
 	if (ret)
 		return ret;
 
-	if ((enable && (nor->bouncebuf[0] & SR2_QUAD_EN_BIT1)) ||
-	    (!enable && !(nor->bouncebuf[0] & SR2_QUAD_EN_BIT1)))
+	if (nor->bouncebuf[0] & SR2_QUAD_EN_BIT1)
 		return 0;
 
-	if (enable)
-		nor->bouncebuf[0] |= SR2_QUAD_EN_BIT1;
-	else
-		nor->bouncebuf[0] &= ~SR2_QUAD_EN_BIT1;
+	nor->bouncebuf[0] |= SR2_QUAD_EN_BIT1;
 
 	return spi_nor_write_16bit_cr_and_check(nor, nor->bouncebuf[0]);
 }
 
 /**
- * spi_nor_sr2_bit7_quad_enable() - set/unset QE bit in Status Register 2.
+ * spi_nor_sr2_bit7_quad_enable() - set QE bit in Status Register 2.
  * @nor:	pointer to a 'struct spi_nor'
- * @enable:	true to enable Quad mode, false to disable Quad mode.
  *
  * Set the Quad Enable (QE) bit in the Status Register 2.
  *
@@ -1983,7 +1971,7 @@ int spi_nor_sr2_bit1_quad_enable(struct spi_nor *nor, bool enable)
  *
  * Return: 0 on success, -errno otherwise.
  */
-int spi_nor_sr2_bit7_quad_enable(struct spi_nor *nor, bool enable)
+int spi_nor_sr2_bit7_quad_enable(struct spi_nor *nor)
 {
 	u8 *sr2 = nor->bouncebuf;
 	int ret;
@@ -1993,15 +1981,11 @@ int spi_nor_sr2_bit7_quad_enable(struct spi_nor *nor, bool enable)
 	ret = spi_nor_read_sr2(nor, sr2);
 	if (ret)
 		return ret;
-	if ((enable && (*sr2 & SR2_QUAD_EN_BIT7)) ||
-	    (!enable && !(*sr2 & SR2_QUAD_EN_BIT7)))
+	if (*sr2 & SR2_QUAD_EN_BIT7)
 		return 0;
 
 	/* Update the Quad Enable bit. */
-	if (enable)
-		*sr2 |= SR2_QUAD_EN_BIT7;
-	else
-		*sr2 &= ~SR2_QUAD_EN_BIT7;
+	*sr2 |= SR2_QUAD_EN_BIT7;
 
 	ret = spi_nor_write_sr2(nor, sr2);
 	if (ret)
@@ -2914,13 +2898,12 @@ static int spi_nor_init_params(struct spi_nor *nor)
 }
 
 /**
- * spi_nor_quad_enable() - enable/disable Quad I/O if needed.
+ * spi_nor_quad_enable() - enable Quad I/O if needed.
  * @nor:                pointer to a 'struct spi_nor'
- * @enable:             true to enable Quad mode. false to disable Quad mode.
  *
  * Return: 0 on success, -errno otherwise.
  */
-static int spi_nor_quad_enable(struct spi_nor *nor, bool enable)
+static int spi_nor_quad_enable(struct spi_nor *nor)
 {
 	if (!nor->params->quad_enable)
 		return 0;
@@ -2929,7 +2912,7 @@ static int spi_nor_quad_enable(struct spi_nor *nor, bool enable)
 	      spi_nor_get_protocol_width(nor->write_proto) == 4))
 		return 0;
 
-	return nor->params->quad_enable(nor, enable);
+	return nor->params->quad_enable(nor);
 }
 
 /**
@@ -2953,7 +2936,7 @@ static int spi_nor_init(struct spi_nor *nor)
 {
 	int err;
 
-	err = spi_nor_quad_enable(nor, true);
+	err = spi_nor_quad_enable(nor);
 	if (err) {
 		dev_dbg(nor->dev, "quad mode not supported\n");
 		return err;
diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
index 95aa32f..6f2f6b2 100644
--- a/drivers/mtd/spi-nor/core.h
+++ b/drivers/mtd/spi-nor/core.h
@@ -198,7 +198,7 @@ struct spi_nor_locking_ops {
  *                      higher index in the array, the higher priority.
  * @erase_map:		the erase map parsed from the SFDP Sector Map Parameter
  *                      Table.
- * @quad_enable:	enables/disables SPI NOR Quad mode.
+ * @quad_enable:	enables SPI NOR quad mode.
  * @set_4byte_addr_mode: puts the SPI NOR in 4 byte addressing mode.
  * @convert_addr:	converts an absolute address into something the flash
  *                      will understand. Particularly useful when pagesize is
@@ -219,7 +219,7 @@ struct spi_nor_flash_parameter {
 
 	struct spi_nor_erase_map        erase_map;
 
-	int (*quad_enable)(struct spi_nor *nor, bool enable);
+	int (*quad_enable)(struct spi_nor *nor);
 	int (*set_4byte_addr_mode)(struct spi_nor *nor, bool enable);
 	u32 (*convert_addr)(struct spi_nor *nor, u32 addr);
 	int (*setup)(struct spi_nor *nor, const struct spi_nor_hwcaps *hwcaps);
@@ -406,9 +406,9 @@ int spi_nor_write_ear(struct spi_nor *nor, u8 ear);
 int spi_nor_wait_till_ready(struct spi_nor *nor);
 int spi_nor_lock_and_prep(struct spi_nor *nor);
 void spi_nor_unlock_and_unprep(struct spi_nor *nor);
-int spi_nor_sr1_bit6_quad_enable(struct spi_nor *nor, bool enable);
-int spi_nor_sr2_bit1_quad_enable(struct spi_nor *nor, bool enable);
-int spi_nor_sr2_bit7_quad_enable(struct spi_nor *nor, bool enable);
+int spi_nor_sr1_bit6_quad_enable(struct spi_nor *nor);
+int spi_nor_sr2_bit1_quad_enable(struct spi_nor *nor);
+int spi_nor_sr2_bit7_quad_enable(struct spi_nor *nor);
 
 int spi_nor_xread_sr(struct spi_nor *nor, u8 *sr);
 ssize_t spi_nor_read_data(struct spi_nor *nor, loff_t from, size_t len,
-- 
2.8.1


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Re: [PATCH 1/2] Revert "mtd: spi-nor: Disable the flash quad mode in spi_nor_restore()"

[Vignesh Raghavendra]

On Fri, 4 Sep 2020 15:47:19 +0800, Yicong Yang wrote:
> Previous patch intends to restore the flash's QE bit when removed/shutdown,
> but may have some problems and break the flash:
> 
> - for those originally in Quad mode, this patch will clear the QE bit
>   when unloaded the flash, which is incorrect.
> - even with above problem solved, it may still break the flash as some
>   flash's QE bit is non-volatile and lots of set/reset will wear out
>   the bit.
> - the restore method cannot be proved to be valid as if a hard
>   reset or accident crash happened, the spi_nor_restore() won't be
>   performed the the QE bit will not be restored as we expected to.
> 
> [...]

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/fixes, thanks!
[1/2] Revert "mtd: spi-nor: Disable the flash quad mode in spi_nor_restore()"
      https://git.kernel.org/mtd/c/7d90a9b269
[2/2] Revert "mtd: spi-nor: Add capability to disable flash quad mode"
      https://git.kernel.org/mtd/c/1afc0c89f6

--
Regards
Vignesh


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