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Date:   Thu, 9 Jan 2020 17:30:28 +0100
From:   Miquel Raynal <miquel.raynal@bootlin.com>
To:     Mason Yang <masonccyang@mxic.com.tw>
Cc:     richard@nod.at, marek.vasut@gmail.com, dwmw2@infradead.org,
        bbrezillon@kernel.org, computersforpeace@gmail.com,
        vigneshr@ti.com, robh+dt@kernel.org, mark.rutland@arm.com,
        devicetree@vger.kernel.org, juliensu@mxic.com.tw,
        linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org
Subject: Re: [PATCH v4 2/2] dt-bindings: mtd: Document Macronix NAND device
 bindings
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In-Reply-To: <1571902807-10388-3-git-send-email-masonccyang@mxic.com.tw>
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        <1571902807-10388-3-git-send-email-masonccyang@mxic.com.tw>
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Hi Mason,

Mason Yang <masonccyang@mxic.com.tw> wrote on Thu, 24 Oct 2019 15:40:07
+0800:

> Document the bindings used by the Macronix NAND device.
> 
> Signed-off-by: Mason Yang <masonccyang@mxic.com.tw>
> ---
>  .../devicetree/bindings/mtd/nand-macronix.txt        | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mtd/nand-macronix.txt
> 
> diff --git a/Documentation/devicetree/bindings/mtd/nand-macronix.txt b/Documentation/devicetree/bindings/mtd/nand-macronix.txt
> new file mode 100644
> index 0000000..cb60358
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mtd/nand-macronix.txt
> @@ -0,0 +1,20 @@
> +Macronix NANDs Device Tree Bindings
> +-----------------------------------
> +
> +Macronix NANDs support randomizer operation for user data scrambled,
> +which can be enabled with a SET_FEATURE. The penalty of randomizer
> +is subpage accesses prohibited. By adding a new specific property
> +in children nodes to enable randomizer function.

You don't mention the performance penalty nor the benefits of such
operation.

Please also insist on the fact that this is a one time persistent, non
reversible operation and the use should use this property only if they
know what they are doing!

> +
> +Required NAND chip properties in children mode:
> +- randomizer enable: should be "mxic,enable-randomizer-otp"
> +
> +Example:
> +
> +	nand: nand-controller@unit-address {
> +
> +		nand@0 {
> +			reg = <0>;
> +			mxic,enable-randomizer-otp;
> +		};
> +	};

Thanks,
Miquèl