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From:   "Lad, Prabhakar" <prabhakar.csengg@gmail.com>
Date:   Mon, 18 May 2020 09:58:57 +0100
Message-ID: <CA+V-a8t6rPs4s8uMCpBQEAUvwsVn7Cte-vX3z2atWRhy_RFLQw@mail.gmail.com>
Subject: Re: [PATCH 03/17] ARM: dts: r8a7742: Add I2C and IIC support
To:     Wolfram Sang <wsa+renesas@sang-engineering.com>
Cc:     Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Jens Axboe <axboe@kernel.dk>, Rob Herring <robh+dt@kernel.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>,
        "David S. Miller" <davem@davemloft.net>,
        Wim Van Sebroeck <wim@linux-watchdog.org>,
        Guenter Roeck <linux@roeck-us.net>, linux-ide@vger.kernel.org,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
        linux-i2c@vger.kernel.org,
        Linux MMC List <linux-mmc@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>,
        Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
        linux-watchdog@vger.kernel.org
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Hi Wolfram,

Thank for the review.

On Fri, May 15, 2020 at 6:10 PM Wolfram Sang
<wsa+renesas@sang-engineering.com> wrote:
>
> On Fri, May 15, 2020 at 04:08:43PM +0100, Lad Prabhakar wrote:
> > Add the I2C[0-3] and IIC[0-3] devices nodes to the R8A7742 device tree.
> >
> > Automatic transmission for PMIC control is not available on IIC3 hence
> > compatible string "renesas,rcar-gen2-iic" and "renesas,rmobile-iic" is
> > not added to iic3 node.
>
> Makes sense.
>
> However, both versions (with and without automatic transmission) are
> described with the same "renesas,iic-r8a7742" compatible. Is it possible
> to detect the reduced variant at runtime somehow?
>
I couldn't find anything the manual that would be useful to detect at runtime.

> My concern is that the peculiarity of this SoC might be forgotten if we
> describe it like this and ever add "automatic transmissions" somewhen.
>
Agreed.

Cheers,
--Prabhakar