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@xxxxxxxxxxx>
> 
> 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@xxxxxxxxxxx>
> ---
>  .../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