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From:   "Lad, Prabhakar" <prabhakar.csengg@gmail.com>
Date:   Mon, 18 May 2020 10:43:26 +0100
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Subject: Re: [PATCH 03/17] ARM: dts: r8a7742: Add I2C and IIC support
To:     Wolfram Sang <wsa+renesas@sang-engineering.com>,
        Geert Uytterhoeven <geert+renesas@glider.be>
Cc:     Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>,
        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,

On Mon, May 18, 2020 at 10:26 AM Wolfram Sang
<wsa+renesas@sang-engineering.com> wrote:
>
>
> > > 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.
>
> Well, I guess reading from a register which is supposed to not be there
> on the modified IP core is too hackish.
>
> Leaves us with a seperate compatible entry for it?
>
Sounds okay to me, how about "renesas,iic-no-dvfs" ? So that this
could be used on all the SoC's which don't support DVFS.

Cheers,
--Prabhakar