linux-kernel - Re: [PATCH 1/2] dt-bindings: spi: Add Socionext F

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Message-ID: <Y3du24GWN/enGORf@sirena.org.uk>
Date:   Fri, 18 Nov 2022 11:39:07 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        linux-spi@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] dt-bindings: spi: Add Socionext F_OSPI controller
 bindings

On Fri, Nov 18, 2022 at 09:59:03AM +0900, Kunihiko Hayashi wrote:

> +  socionext,cs-start-cycle:
> +  socionext,cs-end-cycle:
> +  socionext,cs-deassert-clk-cycle:

These are all generic SPI properties so we should add them
generically, on the device rather than the controller since this
is something that might vary per client device.  There was also a
core function spi_set_cs_timing() which was in earlier versions
and is about to get reintroduced.

> +  socionext,alternative-byte:
> +    description:
> +      Specify the extra bytes to transfer after address transfer.

This just doesn't seem like something the controller should be
worrying about, the device should just send whatever the device
needs sending.  

> +    $ref: /schemas/types.yaml#/definitions/uint32-array
> +    items:
> +      - description: the number of bytes to transfer
> +        maximum: 4
> +      - description: value to transfer
> +        default: 0
> +      - description: bit-width to transfer
> +        enum: [0, 1, 2, 4, 8]

This is also something SPI device should set up, as far as I can
tell this should be set vis spi_mem_op.dummy.nbytes.

> +  socionext,data-swap-2byte:
> +    description:
> +      Indicates swap byte order per 2-bytes.
> +    type: boolean

> +  socionext,data-swap-4byte:
> +    description:
> +      Indicates swap byte order per 4-bytes.
> +    type: boolean

Again these should be set by the device.  I think these should be
set based on a combination of bits per word and if the host is in
big endian or little endian mode.

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