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Subject: Re: [PATCH v10 3/3] dt-bindings: mfd: Document Renesas R-Car Gen3
 RPC-IF controller bindings
From:   Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
To:     masonccyang@mxic.com.tw
Cc:     bbrezillon@kernel.org, broonie@kernel.org,
        devicetree@vger.kernel.org,
        Geert Uytterhoeven <geert+renesas@glider.be>,
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        lee.jones@linaro.org, linux-kernel@vger.kernel.org,
        linux-renesas-soc@vger.kernel.org, linux-spi@vger.kernel.org,
        marek.vasut@gmail.com, mark.rutland@arm.com, robh+dt@kernel.org
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Date:   Fri, 19 Apr 2019 18:44:38 +0300
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On 04/18/2019 07:55 PM, Sergei Shtylyov wrote:

>>>>  > > Document the bindings used by the Renesas R-Car Gen3 RPC-IF
>>> MFD controller.
>>>>  > >
>>>>  > > Signed-off-by: Mason Yang <masonccyang@mxic.com.tw>
>>>>  > > ---
>>>>  > >  .../devicetree/bindings/mfd/mfd-renesas-rpc.txt  | 37 +++++++++
>>>>  > +++++++++++++
>>>>  > >  1 file changed, 37 insertions(+)
>>>>  > >  create mode 100644 Documentation/devicetree/bindings/mfd/mfd-
>>>>  > renesas-rpc.txt
>>>>  > >
>>>>  > > diff --git a/Documentation/devicetree/bindings/mfd/mfd-renesas-
>>>>  > rpc.txt b/Documentation/devicetree/bindings/mfd/mfd-renesas-rpc.txt
>>>>  > > new file mode 100644
>>>>  > > index 0000000..bfb3d29
>>>>  > > --- /dev/null
>>>>  > > +++ b/Documentation/devicetree/bindings/mfd/mfd-renesas-rpc.txt
>>>>  > > @@ -0,0 +1,37 @@
>>>>  > > +Renesas R-Car Gen3 RPC-IF MFD controller Device Tree Bindings
>>>>  > > +-------------------------------------------------------------
>>>>  > > +
>>>>  > > +Required properties:
>>>>  > > +- compatible: should be an SoC-specific compatible value, followed by
>>>>  > > +      "renesas,rcar-gen3-rpc" as a fallback.
>>>>  > > +      supported SoC-specific values are:
>>>>  > > +      "renesas,r8a77995-rpc" (R-Car D3)
>>>>  > > +- reg: should contain 2 entries, one for the base address of rpc-
>>>>  > if registers,
>>>>  > > +   and one for the direct mapping area
>>>>  > > +- reg-names: should contain "regs", and "dirmap"
>>>>  >
>>>>  >    The device tree describes the hardware, not the driver. Why
>>> did you remove
>>>>  > the "wbuf" area?
>>>>
>>>> I don't think we should describe the hardware that driver did not
>>> implement it
>>>> because there are still many RPC registers we don't use them.
>>>
>>>     I have to repeat: we describe the hardware, not the driver capabilities.
>>
>> how about:
>>
>> - reg: should contain three register areas:
>>           first for the base address of rpc-if registers,
>>           second for the direct mapping read mode and
>>           third for an optional write buffer area.
>>  - reg-names: should contain "regs", "dirmap" and "wbuf"(optional).
>>
>> is it OK ?
> 
>    No, the write buffer area is always there, at least on the gen3 chips.
> (I forgot which other Renesas SoC has RPC-IF as well).

   So it was RZ/A1. But it didn't have the HyperFlash mode...

>> thanks & best regards,
>> Mason

MBR, Sergei