[PATCH v8 0/3] mtd: spi-nand: Add support for randomizer feature

[PATCH v8 0/3] mtd: spi-nand: Add support for randomizer feature

[Cheng Ming Lin]

From: Cheng Ming Lin <chengminglin@mxic.com.tw>

This patch series introduces randomizer support for SPI NAND devices.

- Patch 1: add the nand-randomizer-enable and nand-randomizer-disable
           boolean properties to the generic nand-chip.yaml bindings.
- Patch 2: add the initialization logic and the set_randomizer callback
           to the core framework. The core will now parse the device tree
           properties and enable or disable the randomizer accordingly
           during spinand_init.
- Patch 3: implement the set_randomizer callback specifically for Macronix
           chips (MX35LF/UF series) to handle the vendor-specific register
           operations.

v8:
* dt-bindings: spi-nand: macronix: Remove the chip-specific Application
  Note link from the commit message to keep the binding generic.
* mtd: spi-nand: macronix: Update the broken Application Note link and
  move it here from the dt-binding patch per Miquel's suggestion.

v7:
* Directly return the result in macronix_set_randomizer()

v6:
* Added mutual-exclusive constraints using not with required for
  nand-randomizer-enable and nand-randomizer-disable properties based
  on Krzysztof's feedback.
* Simplified the return path in macronix_set_randomizer() to directly
  return ret; and dropped unrelated formatting changes.

v5:
* Promoted the randomizer configuration to use generic NAND properties
  (nand-randomizer-enable and nand-randomizer-disable) instead of
  vendor-specific bindings.
* Refactored the initialization architecture in core.c. The core framework
  is now responsible for parsing the device tree properties and deciding
  whether to enable or disable the randomizer.

v4:
* Fix a build error in spinand_randomizer_init() where a value was
  returned from a void function. (Reported by kernel test robot)
* Update the return type to int.

v3:
* Revert the device tree property to the vendor-specific
  "mxic,randomizer-enable" to strictly follow vendor-specific bindings.

* Update the 'set_randomizer' callback signature to accept a boolean
  'enable' argument, allowing the feature to be explicitly enabled or
  disabled.

* Switch the implementation to use the standard SET_FEATURE command
  to modify the Configuration Register (0x10), replacing the previous
  special program command method.

v2:
* Create a global NAND DT property

Cheng Ming Lin (3):
  dt-bindings: mtd: spinand: Add randomizer enable/disable properties
  mtd: spi-nand: Add support for randomizer
  mtd: spi-nand: macronix: Enable randomizer support

 .../devicetree/bindings/mtd/nand-chip.yaml    | 18 +++++++++
 drivers/mtd/nand/spi/core.c                   | 27 +++++++++++++
 drivers/mtd/nand/spi/macronix.c               | 38 ++++++++++++++-----
 include/linux/mtd/spinand.h                   |  9 +++++
 4 files changed, 82 insertions(+), 10 deletions(-)

-- 
2.25.1


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[PATCH v8 1/3] dt-bindings: mtd: spinand: Add randomizer enable/disable properties

[Cheng Ming Lin]

From: Cheng Ming Lin <chengminglin@mxic.com.tw>

Add "nand-randomizer-enable" and "nand-randomizer-disable" boolean
properties.

These properties allow enabling or disabling the randomizer feature
via the device tree.

According to JEDEC standard JESD22-A117E, no single data pattern
represents a universal worst-case for all NAND flash failure mechanisms.
Different patterns, such as fully programmed, checkerboard, or mostly
erased, can disproportionately stress specific cells (e.g., programmed,
erased, or those influenced by adjacent states).

Given that no fixed pattern can cover all scenarios, the use of a
randomized data pattern is a practical and effective mitigation strategy.
Our hardware implements a randomizer feature that scrambles user data
before it is written to the flash and restores the original data upon read.

This ensures the data stored on the media is more evenly distributed,
thus reducing pattern-dependent degradation. This is especially crucial
for preventing errors caused by unbalanced data (e.g., all zeros or
all ones) in blocks with high program/erase (P/E) cycle counts.
Ultimately, the randomizer improves the long-term reliability and
endurance of the flash device.

Signed-off-by: Cheng Ming Lin <chengminglin@mxic.com.tw>
---
 .../devicetree/bindings/mtd/nand-chip.yaml     | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/Documentation/devicetree/bindings/mtd/nand-chip.yaml b/Documentation/devicetree/bindings/mtd/nand-chip.yaml
index 609d4a4ddd80..2559cd97ccc5 100644
--- a/Documentation/devicetree/bindings/mtd/nand-chip.yaml
+++ b/Documentation/devicetree/bindings/mtd/nand-chip.yaml
@@ -67,6 +67,24 @@ properties:
       the secure regions present.
     $ref: /schemas/types.yaml#/definitions/uint64-matrix
 
+  nand-randomizer-enable:
+    description:
+      Enable the randomizer feature. This property is mutually-exclusive
+      with nand-randomizer-disable.
+    type: boolean
+
+  nand-randomizer-disable:
+    description:
+      Disable the randomizer feature. This property is mutually-exclusive
+      with nand-randomizer-enable.
+    type: boolean
+
+dependencies:
+  nand-randomizer-enable:
+    not:
+      required:
+        - nand-randomizer-disable
+
 required:
   - reg
 
-- 
2.25.1


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[PATCH v8 2/3] mtd: spi-nand: Add support for randomizer

[Cheng Ming Lin]

From: Cheng Ming Lin <chengminglin@mxic.com.tw>

This patch adds support for the randomizer feature.

It introduces a 'set_randomizer' callback in 'struct spinand_info' and
'struct spinand_device'.

If a driver implements this callback, the core will invoke it during
device initialization (spinand_init) to enable or disable the randomizer
feature based on the device tree configuration.

Signed-off-by: Cheng Ming Lin <chengminglin@mxic.com.tw>
---
 drivers/mtd/nand/spi/core.c | 27 +++++++++++++++++++++++++++
 include/linux/mtd/spinand.h |  9 +++++++++
 2 files changed, 36 insertions(+)

diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
index 8aa3753aaaa1..77a0371010c4 100644
--- a/drivers/mtd/nand/spi/core.c
+++ b/drivers/mtd/nand/spi/core.c
@@ -1307,6 +1307,29 @@ static int spinand_create_dirmaps(struct spinand_device *spinand)
 	return 0;
 }
 
+static int spinand_randomizer_init(struct spinand_device *spinand)
+{
+	struct device_node *np = spinand->spimem->spi->dev.of_node;
+	bool enable = false;
+	int ret;
+
+	if (!spinand->set_randomizer)
+		return 0;
+
+	if (of_property_read_bool(np, "nand-enable-randomizer"))
+		enable = true;
+	else if (of_property_read_bool(np, "nand-disable-randomizer"))
+		enable = false;
+	else
+		return 0;
+
+	ret = spinand->set_randomizer(spinand, enable);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
 static const struct nand_ops spinand_ops = {
 	.erase = spinand_erase,
 	.markbad = spinand_markbad,
@@ -1594,6 +1617,7 @@ int spinand_match_and_init(struct spinand_device *spinand,
 		spinand->user_otp = &table[i].user_otp;
 		spinand->read_retries = table[i].read_retries;
 		spinand->set_read_retry = table[i].set_read_retry;
+		spinand->set_randomizer = table[i].set_randomizer;
 
 		/* I/O variants selection with single-spi SDR commands */
 
@@ -1881,6 +1905,9 @@ static int spinand_init(struct spinand_device *spinand)
 	 * ECC initialization must have happened previously.
 	 */
 	spinand_cont_read_init(spinand);
+	ret = spinand_randomizer_init(spinand);
+	if (ret)
+		goto err_cleanup_nanddev;
 
 	mtd->_read_oob = spinand_mtd_read;
 	mtd->_write_oob = spinand_mtd_write;
diff --git a/include/linux/mtd/spinand.h b/include/linux/mtd/spinand.h
index 6a024cf1c53a..6a68a6c3866a 100644
--- a/include/linux/mtd/spinand.h
+++ b/include/linux/mtd/spinand.h
@@ -584,6 +584,7 @@ enum spinand_bus_interface {
  * @user_otp: SPI NAND user OTP info.
  * @read_retries: the number of read retry modes supported
  * @set_read_retry: enable/disable read retry for data recovery
+ * @set_randomizer: enable/disable randomizer support
  *
  * Each SPI NAND manufacturer driver should have a spinand_info table
  * describing all the chips supported by the driver.
@@ -612,6 +613,8 @@ struct spinand_info {
 	unsigned int read_retries;
 	int (*set_read_retry)(struct spinand_device *spinand,
 			     unsigned int read_retry);
+	int (*set_randomizer)(struct spinand_device *spinand,
+			      bool enable);
 };
 
 #define SPINAND_ID(__method, ...)					\
@@ -668,6 +671,9 @@ struct spinand_info {
 	.read_retries = __read_retries,					\
 	.set_read_retry = __set_read_retry
 
+#define SPINAND_RANDOMIZER(__set_randomizer)				\
+	.set_randomizer = __set_randomizer
+
 #define SPINAND_INFO(__model, __id, __memorg, __eccreq, __op_variants,	\
 		     __flags, ...)					\
 	{								\
@@ -753,6 +759,7 @@ struct spinand_mem_ops {
  * @user_otp: SPI NAND user OTP info.
  * @read_retries: the number of read retry modes supported
  * @set_read_retry: Enable/disable the read retry feature
+ * @set_randomizer: Enable/disable the randomizer feature
  */
 struct spinand_device {
 	struct nand_device base;
@@ -786,6 +793,8 @@ struct spinand_device {
 	bool cont_read_possible;
 	int (*set_cont_read)(struct spinand_device *spinand,
 			     bool enable);
+	int (*set_randomizer)(struct spinand_device *spinand,
+			      bool enable);
 
 	const struct spinand_fact_otp *fact_otp;
 	const struct spinand_user_otp *user_otp;
-- 
2.25.1


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[PATCH v8 3/3] mtd: spi-nand: macronix: Enable randomizer support

[Cheng Ming Lin]

From: Cheng Ming Lin <chengminglin@mxic.com.tw>

Implement the 'set_randomizer' callback for Macronix SPI NAND chips.
The randomizer is enabled by setting bit 1 of the Configuration Register
(address 0x10).

This patch adds support for the following chips:
  - MX35LFxG24AD series
  - MX35UFxG24AD series

When the randomizer is enabled, data is scrambled internally during
program operations and automatically descrambled during read operations.
This helps reduce bit errors caused by program disturbance.

Please refer to the following link for randomizer feature:
Link: https://www.mxic.com.tw/Lists/ApplicationNote/Attachments/2151/AN1051V1-The%20Introduction%20of%20Randomizer%20Feature%20on%20MX30xFxG28AD_MX35xFxG24AD.pdf

Signed-off-by: Cheng Ming Lin <chengminglin@mxic.com.tw>
---
 drivers/mtd/nand/spi/macronix.c | 38 ++++++++++++++++++++++++---------
 1 file changed, 28 insertions(+), 10 deletions(-)

diff --git a/drivers/mtd/nand/spi/macronix.c b/drivers/mtd/nand/spi/macronix.c
index 67cafa1bb8ef..7dfcc34e9b72 100644
--- a/drivers/mtd/nand/spi/macronix.c
+++ b/drivers/mtd/nand/spi/macronix.c
@@ -14,6 +14,8 @@
 #define MACRONIX_ECCSR_BF_LAST_PAGE(eccsr) FIELD_GET(GENMASK(3, 0), eccsr)
 #define MACRONIX_ECCSR_BF_ACCUMULATED_PAGES(eccsr) FIELD_GET(GENMASK(7, 4), eccsr)
 #define MACRONIX_CFG_CONT_READ         BIT(2)
+#define MACRONIX_CFG_RANDOMIZER_EN     BIT(1)
+#define MACRONIX_FEATURE_ADDR_RANDOMIZER 0x10
 #define MACRONIX_FEATURE_ADDR_READ_RETRY 0x70
 #define MACRONIX_NUM_READ_RETRY_MODES 5
 
@@ -170,6 +172,12 @@ static int macronix_set_read_retry(struct spinand_device *spinand,
 	return spi_mem_exec_op(spinand->spimem, &op);
 }
 
+static int macronix_set_randomizer(struct spinand_device *spinand, bool enable)
+{
+	return spinand_write_reg_op(spinand, MACRONIX_FEATURE_ADDR_RANDOMIZER,
+				    enable ? MACRONIX_CFG_RANDOMIZER_EN : 0);
+}
+
 static const struct spinand_info macronix_spinand_table[] = {
 	SPINAND_INFO("MX35LF1GE4AB",
 		     SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0x12),
@@ -231,7 +239,8 @@ static const struct spinand_info macronix_spinand_table[] = {
 		     SPINAND_HAS_QE_BIT,
 		     SPINAND_ECCINFO(&mx35lfxge4ab_ooblayout, NULL),
 		     SPINAND_READ_RETRY(MACRONIX_NUM_READ_RETRY_MODES,
-					macronix_set_read_retry)),
+					macronix_set_read_retry),
+		     SPINAND_RANDOMIZER(macronix_set_randomizer)),
 	SPINAND_INFO("MX35LF2G24AD",
 		     SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0x24, 0x03),
 		     NAND_MEMORG(1, 2048, 128, 64, 2048, 40, 2, 1, 1),
@@ -243,7 +252,8 @@ static const struct spinand_info macronix_spinand_table[] = {
 		     SPINAND_HAS_PROG_PLANE_SELECT_BIT,
 		     SPINAND_ECCINFO(&mx35lfxge4ab_ooblayout, NULL),
 		     SPINAND_READ_RETRY(MACRONIX_NUM_READ_RETRY_MODES,
-					macronix_set_read_retry)),
+					macronix_set_read_retry),
+		     SPINAND_RANDOMIZER(macronix_set_randomizer)),
 	SPINAND_INFO("MX35LF2G24AD-Z4I8",
 		     SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0x64, 0x03),
 		     NAND_MEMORG(1, 2048, 128, 64, 2048, 40, 1, 1, 1),
@@ -254,7 +264,8 @@ static const struct spinand_info macronix_spinand_table[] = {
 		     SPINAND_HAS_QE_BIT,
 		     SPINAND_ECCINFO(&mx35lfxge4ab_ooblayout, NULL),
 		     SPINAND_READ_RETRY(MACRONIX_NUM_READ_RETRY_MODES,
-					macronix_set_read_retry)),
+					macronix_set_read_retry),
+		     SPINAND_RANDOMIZER(macronix_set_randomizer)),
 	SPINAND_INFO("MX35LF4G24AD",
 		     SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0x35, 0x03),
 		     NAND_MEMORG(1, 4096, 256, 64, 2048, 40, 2, 1, 1),
@@ -266,7 +277,8 @@ static const struct spinand_info macronix_spinand_table[] = {
 		     SPINAND_HAS_PROG_PLANE_SELECT_BIT,
 		     SPINAND_ECCINFO(&mx35lfxge4ab_ooblayout, NULL),
 		     SPINAND_READ_RETRY(MACRONIX_NUM_READ_RETRY_MODES,
-					macronix_set_read_retry)),
+					macronix_set_read_retry),
+		     SPINAND_RANDOMIZER(macronix_set_randomizer)),
 	SPINAND_INFO("MX35LF4G24AD-Z4I8",
 		     SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0x75, 0x03),
 		     NAND_MEMORG(1, 4096, 256, 64, 2048, 40, 1, 1, 1),
@@ -277,7 +289,8 @@ static const struct spinand_info macronix_spinand_table[] = {
 		     SPINAND_HAS_QE_BIT,
 		     SPINAND_ECCINFO(&mx35lfxge4ab_ooblayout, NULL),
 		     SPINAND_READ_RETRY(MACRONIX_NUM_READ_RETRY_MODES,
-					macronix_set_read_retry)),
+					macronix_set_read_retry),
+		     SPINAND_RANDOMIZER(macronix_set_randomizer)),
 	SPINAND_INFO("MX31LF1GE4BC",
 		     SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0x1e),
 		     NAND_MEMORG(1, 2048, 64, 64, 1024, 20, 1, 1, 1),
@@ -327,7 +340,8 @@ static const struct spinand_info macronix_spinand_table[] = {
 		     SPINAND_ECCINFO(&mx35lfxge4ab_ooblayout,
 				     macronix_ecc_get_status),
 		     SPINAND_READ_RETRY(MACRONIX_NUM_READ_RETRY_MODES,
-					macronix_set_read_retry)),
+					macronix_set_read_retry),
+		     SPINAND_RANDOMIZER(macronix_set_randomizer)),
 	SPINAND_INFO("MX35UF4G24AD-Z4I8",
 		     SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0xf5, 0x03),
 		     NAND_MEMORG(1, 4096, 256, 64, 2048, 40, 1, 1, 1),
@@ -340,7 +354,8 @@ static const struct spinand_info macronix_spinand_table[] = {
 		     SPINAND_ECCINFO(&mx35lfxge4ab_ooblayout,
 				     macronix_ecc_get_status),
 		     SPINAND_READ_RETRY(MACRONIX_NUM_READ_RETRY_MODES,
-					macronix_set_read_retry)),
+					macronix_set_read_retry),
+		     SPINAND_RANDOMIZER(macronix_set_randomizer)),
 	SPINAND_INFO("MX35UF4GE4AD",
 		     SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0xb7, 0x03),
 		     NAND_MEMORG(1, 4096, 256, 64, 2048, 40, 1, 1, 1),
@@ -381,7 +396,8 @@ static const struct spinand_info macronix_spinand_table[] = {
 		     SPINAND_ECCINFO(&mx35lfxge4ab_ooblayout,
 				     macronix_ecc_get_status),
 		     SPINAND_READ_RETRY(MACRONIX_NUM_READ_RETRY_MODES,
-					macronix_set_read_retry)),
+					macronix_set_read_retry),
+		     SPINAND_RANDOMIZER(macronix_set_randomizer)),
 	SPINAND_INFO("MX35UF2G24AD-Z4I8",
 		     SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0xe4, 0x03),
 		     NAND_MEMORG(1, 2048, 128, 64, 2048, 40, 1, 1, 1),
@@ -394,7 +410,8 @@ static const struct spinand_info macronix_spinand_table[] = {
 		     SPINAND_ECCINFO(&mx35lfxge4ab_ooblayout,
 				     macronix_ecc_get_status),
 		     SPINAND_READ_RETRY(MACRONIX_NUM_READ_RETRY_MODES,
-					macronix_set_read_retry)),
+					macronix_set_read_retry),
+		     SPINAND_RANDOMIZER(macronix_set_randomizer)),
 	SPINAND_INFO("MX35UF2GE4AD",
 		     SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0xa6, 0x03),
 		     NAND_MEMORG(1, 2048, 128, 64, 2048, 40, 1, 1, 1),
@@ -444,7 +461,8 @@ static const struct spinand_info macronix_spinand_table[] = {
 		     SPINAND_ECCINFO(&mx35lfxge4ab_ooblayout,
 				     macronix_ecc_get_status),
 		     SPINAND_READ_RETRY(MACRONIX_NUM_READ_RETRY_MODES,
-					macronix_set_read_retry)),
+					macronix_set_read_retry),
+		     SPINAND_RANDOMIZER(macronix_set_randomizer)),
 	SPINAND_INFO("MX35UF1GE4AD",
 		     SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0x96, 0x03),
 		     NAND_MEMORG(1, 2048, 128, 64, 1024, 20, 1, 1, 1),
-- 
2.25.1


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Re: [PATCH v8 0/3] mtd: spi-nand: Add support for randomizer feature

[Miquel Raynal]

Hello Cheng Ming,

On 05/03/2026 at 15:10:39 +08, Cheng Ming Lin <linchengming884@gmail.com> wrote:

> From: Cheng Ming Lin <chengminglin@mxic.com.tw>
>
> This patch series introduces randomizer support for SPI NAND devices.
>
> - Patch 1: add the nand-randomizer-enable and nand-randomizer-disable
>            boolean properties to the generic nand-chip.yaml bindings.
> - Patch 2: add the initialization logic and the set_randomizer callback
>            to the core framework. The core will now parse the device tree
>            properties and enable or disable the randomizer accordingly
>            during spinand_init.
> - Patch 3: implement the set_randomizer callback specifically for Macronix
>            chips (MX35LF/UF series) to handle the vendor-specific register
>            operations.

MTD part LGTM. Let's see if the dt-binding are ok, they look fine.

Thanks,
Miquèl

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Re: [PATCH v8 1/3] dt-bindings: mtd: spinand: Add randomizer enable/disable properties

[Rob Herring]

On Thu, Mar 05, 2026 at 03:10:40PM +0800, Cheng Ming Lin wrote:
> From: Cheng Ming Lin <chengminglin@mxic.com.tw>
> 
> Add "nand-randomizer-enable" and "nand-randomizer-disable" boolean
> properties.
> 
> These properties allow enabling or disabling the randomizer feature
> via the device tree.
> 
> According to JEDEC standard JESD22-A117E, no single data pattern
> represents a universal worst-case for all NAND flash failure mechanisms.
> Different patterns, such as fully programmed, checkerboard, or mostly
> erased, can disproportionately stress specific cells (e.g., programmed,
> erased, or those influenced by adjacent states).
> 
> Given that no fixed pattern can cover all scenarios, the use of a
> randomized data pattern is a practical and effective mitigation strategy.
> Our hardware implements a randomizer feature that scrambles user data
> before it is written to the flash and restores the original data upon read.
> 
> This ensures the data stored on the media is more evenly distributed,
> thus reducing pattern-dependent degradation. This is especially crucial
> for preventing errors caused by unbalanced data (e.g., all zeros or
> all ones) in blocks with high program/erase (P/E) cycle counts.
> Ultimately, the randomizer improves the long-term reliability and
> endurance of the flash device.
> 
> Signed-off-by: Cheng Ming Lin <chengminglin@mxic.com.tw>
> ---
>  .../devicetree/bindings/mtd/nand-chip.yaml     | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/mtd/nand-chip.yaml b/Documentation/devicetree/bindings/mtd/nand-chip.yaml
> index 609d4a4ddd80..2559cd97ccc5 100644
> --- a/Documentation/devicetree/bindings/mtd/nand-chip.yaml
> +++ b/Documentation/devicetree/bindings/mtd/nand-chip.yaml
> @@ -67,6 +67,24 @@ properties:
>        the secure regions present.
>      $ref: /schemas/types.yaml#/definitions/uint64-matrix
>  
> +  nand-randomizer-enable:
> +    description:
> +      Enable the randomizer feature. This property is mutually-exclusive
> +      with nand-randomizer-disable.
> +    type: boolean
> +
> +  nand-randomizer-disable:
> +    description:
> +      Disable the randomizer feature. This property is mutually-exclusive
> +      with nand-randomizer-enable.
> +    type: boolean
> +
> +dependencies:
> +  nand-randomizer-enable:
> +    not:
> +      required:
> +        - nand-randomizer-disable

Rather than define this in the schema, make the properties inheritly 
mutually-exclusive with a single property:

nand-randomizer = <0|1>;

That's assuming you need not present to mean a 3rd thing such as use the 
bootloader setting. If you only need enable/disable, then a 
single boolean property works.

Rob

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Re: [PATCH v8 1/3] dt-bindings: mtd: spinand: Add randomizer enable/disable properties

[Miquel Raynal]

>> +  nand-randomizer-enable:
>> +    description:
>> +      Enable the randomizer feature. This property is mutually-exclusive
>> +      with nand-randomizer-disable.
>> +    type: boolean
>> +
>> +  nand-randomizer-disable:
>> +    description:
>> +      Disable the randomizer feature. This property is mutually-exclusive
>> +      with nand-randomizer-enable.
>> +    type: boolean
>> +
>> +dependencies:
>> +  nand-randomizer-enable:
>> +    not:
>> +      required:
>> +        - nand-randomizer-disable
>
> Rather than define this in the schema, make the properties inheritly 
> mutually-exclusive with a single property:
>
> nand-randomizer = <0|1>;
>
> That's assuming you need not present to mean a 3rd thing such as use the 
> bootloader setting. If you only need enable/disable, then a 
> single boolean property works.

We need the "not present" case, so the single boolean property cannot
be considered here.

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