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Subject: Re: [PATCH 1/2] spi: support inter-word delay requirement for devices
To:     Mark Brown <broonie@kernel.org>,
        Geert Uytterhoeven <geert@linux-m68k.org>
Cc:     Baolin Wang <baolin.wang@linaro.org>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-spi <linux-spi@vger.kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        DTML <devicetree@vger.kernel.org>
References: <20190125114429.20066-1-jonas@norrbonn.se>
 <20190125114429.20066-2-jonas@norrbonn.se>
 <CAMz4ku+sqzK19994BpdSfaDjNdXW_-gnCutr_fYQiv5ynxOq2g@mail.gmail.com>
 <f34151c8-28a3-3d53-a27e-b5ff512d9c94@norrbonn.se>
 <20190125174713.GA6939@sirena.org.uk> <20190125175031.GA25898@sirena.org.uk>
 <84d6c40f-62bb-fd00-0dcb-d2f390b136c1@norrbonn.se>
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 <CAMuHMdXQONq1UFuFHwny_xfAtxY7sOv2K3yi2i9T22OovMqFhw@mail.gmail.com>
 <20190128114757.GA11699@sirena.org.uk>
From:   Jonas Bonn <jonas@norrbonn.se>
Message-ID: <94c7514c-de1f-ff70-d2b7-6394f9747942@norrbonn.se>
Date:   Mon, 28 Jan 2019 12:51:02 +0100
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On 28/01/2019 12:47, Mark Brown wrote:
> On Mon, Jan 28, 2019 at 08:41:05AM +0100, Geert Uytterhoeven wrote:
>> On Sat, Jan 26, 2019 at 4:40 PM Jonas Bonn <jonas@norrbonn.se> wrote:
> 
>>> spi-3wire: again, only set by MAXIM DS-1302 which always needs this
>>> setting; driver could set this
> 
>> For DS1302, this is probable true.
>> Some devices may support both 4-wire or 3-wire mode?
> 
> IIRC yes.

Just for the record, the datasheet says it's exclusively 3-wire.  But 
it's not important...

/Jonas

> 
>>> Yeah, that one make sense.  But if the DT is only overriding the maximum
>>> device frequency that the driver should otherwise be setting, why is
>>> spi-max-frequency a _required_ property?
> 
>> That's a good question. Legacy?
> 
> It's a documentation error.
>