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Date: Mon, 6 May 2024 15:48:58 +0200
From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Arseniy Krasnov <avkrasnov@salutedevices.com>
Cc: Richard Weinberger <richard@nod.at>, Vignesh Raghavendra
 <vigneshr@ti.com>, Rob Herring <robh+dt@kernel.org>, Krzysztof Kozlowski
 <krzysztof.kozlowski+dt@linaro.org>, Conor Dooley <conor+dt@kernel.org>,
 Neil Armstrong <neil.armstrong@linaro.org>, Kevin Hilman
 <khilman@baylibre.com>, Jerome Brunet <jbrunet@baylibre.com>, Martin
 Blumenstingl <martin.blumenstingl@googlemail.com>,
 <linux-mtd@lists.infradead.org>, <devicetree@vger.kernel.org>,
 <linux-arm-kernel@lists.infradead.org>,
 <linux-amlogic@lists.infradead.org>, <linux-kernel@vger.kernel.org>,
 <oxffffaa@gmail.com>, <kernel@sberdevices.ru>
Subject: Re: [PATCH v5 1/2] dt-bindings: mtd: amlogic,meson-nand: support
 fields for boot ROM code
Message-ID: <20240506154858.003bab54@xps-13>
In-Reply-To: <20240416085101.740458-2-avkrasnov@salutedevices.com>
References: <20240416085101.740458-1-avkrasnov@salutedevices.com>
	<20240416085101.740458-2-avkrasnov@salutedevices.com>
Organization: Bootlin
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Hi Arseniy,

avkrasnov@salutedevices.com wrote on Tue, 16 Apr 2024 11:51:00 +0300:

> Boot ROM code on Meson requires that some pages on NAND must be written
> in special mode: "short" ECC mode where each block is 384 bytes and
> scrambling mode is on.

Ok

> Such pages located with the specified interval within specified offset.

I'm sorry I don't get that sentence.

> Both interval and offset are located in the
> device tree and used by driver if 'nand-is-boot-medium' is set for
> NAND chip.

This sentence is probably not needed.

>=20
> Signed-off-by: Arseniy Krasnov <avkrasnov@salutedevices.com>
> ---
>  .../bindings/mtd/amlogic,meson-nand.yaml           | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>=20
> diff --git a/Documentation/devicetree/bindings/mtd/amlogic,meson-nand.yam=
l b/Documentation/devicetree/bindings/mtd/amlogic,meson-nand.yaml
> index 57b6957c8415..67b2f7c1259c 100644
> --- a/Documentation/devicetree/bindings/mtd/amlogic,meson-nand.yaml
> +++ b/Documentation/devicetree/bindings/mtd/amlogic,meson-nand.yaml
> @@ -64,11 +64,25 @@ patternProperties:
>          items:
>            maximum: 0
> =20
> +      amlogic,boot-pages:
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +        description:
> +          Number of pages starting from 0, where special ECC

from *offset* 0 I guess?

> +          algorithm will be used by the driver.

"where a special ECC configuration must be used because it is accessed
by the ROM code"? Maybe you can even detail what are these values if
they are fixed.

You should probably inform that scrambling shall be on as well.
=20
> +
> +      amlogic,boot-page-step:
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +        description:
> +          Interval between pages, read/written by the driver with
> +          special ECC algorithm.

I'm not sure I fully get the description. What is the unit here? can
you draw a small ascii-art diagram?

> +
>      unevaluatedProperties: false
> =20
>      dependencies:
>        nand-ecc-strength: [nand-ecc-step-size]
>        nand-ecc-step-size: [nand-ecc-strength]
> +      amlogic,boot-pages: [nand-is-boot-medium, "amlogic,boot-page-step"]
> +      amlogic,boot-page-step: [nand-is-boot-medium, "amlogic,boot-pages"]
> =20
> =20
>  required:


Thanks,
Miqu=C3=A8l