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Subject: Re: [PATCH v5 2/2] dt-bindings: spi: Document Renesas R-Car RPC-IF
 controller bindings
To:     Mason Yang <masonccyang@mxic.com.tw>, broonie@kernel.org,
        linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org,
        boris.brezillon@bootlin.com, linux-renesas-soc@vger.kernel.org,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        sergei.shtylyov@cogentembedded.com
Cc:     juliensu@mxic.com.tw, Simon Horman <horms@verge.net.au>,
        zhengxunli@mxic.com.tw
References: <1546921020-20436-1-git-send-email-masonccyang@mxic.com.tw>
 <1546921020-20436-3-git-send-email-masonccyang@mxic.com.tw>
From:   Marek Vasut <marek.vasut@gmail.com>
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Date:   Tue, 8 Jan 2019 12:52:41 +0100
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On 1/8/19 5:17 AM, Mason Yang wrote:
> Document the bindings used by the Renesas R-Car Gen3 RPC-IF controller.
> 
> Signed-off-by: Mason Yang <masonccyang@mxic.com.tw>
> ---
>  .../devicetree/bindings/spi/spi-renesas-rpc.txt    | 37 ++++++++++++++++++++++
>  1 file changed, 37 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/spi/spi-renesas-rpc.txt
> 
> diff --git a/Documentation/devicetree/bindings/spi/spi-renesas-rpc.txt b/Documentation/devicetree/bindings/spi/spi-renesas-rpc.txt
> new file mode 100644
> index 0000000..5f96532
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/spi/spi-renesas-rpc.txt
> @@ -0,0 +1,37 @@
> +Renesas R-Car Gen3 RPC-IF controller Device Tree Bindings
> +----------------------------------------------------------
> +
> +Required properties:
> +- compatible: should be "renesas,r8a77995-rpc"
> +- #address-cells: should be 1
> +- #size-cells: should be 0
> +- reg: should contain 2 entries, one for the registers and one for the direct
> +       mapping area
> +- reg-names: should contain "regs" and "dirmap"
> +- clock-names: should contain "rpc"
> +- clocks: should contain 1 entries for the module's clock
> +- renesas,rpc-mode: should contain "spi" for rpc spi mode or
> +			   	   "hyperflash" for rpc hyperflash mode.

Why do we need this property ? I believe it is possible to detect the
configuration based on the type of child of the RPC node. If the driver
was properly designed, it could well behave as either CFI NOR driver or
SPI flash driver and all would be good, but it seems this is written
with it being SPI flash driver only and once the HF mode would need to
be added, it'd mean a tremendous undertaking to rework the entire driver.

-- 
Best regards,
Marek Vasut