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Date:   Thu, 27 Feb 2020 16:44:25 +0000
From:   Mark Brown <broonie@kernel.org>
To:     Geert Uytterhoeven <geert@linux-m68k.org>
Cc:     Boris Brezillon <boris.brezillon@collabora.com>,
        Mark Rutland <mark.rutland@arm.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Tudor Ambarus <tudor.ambarus@microchip.com>,
        Richard Weinberger <richard@nod.at>,
        Sekhar Nori <nsekhar@ti.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-spi <linux-spi@vger.kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        MTD Maling List <linux-mtd@lists.infradead.org>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Pratyush Yadav <p.yadav@ti.com>
Subject: Re: [PATCH v2 01/11] dt-bindings: spi: allow expressing DTR
 capability
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On Thu, Feb 27, 2020 at 05:40:31PM +0100, Geert Uytterhoeven wrote:
> On Thu, Feb 27, 2020 at 5:28 PM Mark Brown <broonie@kernel.org> wrote:

> > It's what we do for other properties, and if this is anything like the
> > other things adding extra wiring you can't assume that the ability to
> > use the feature for TX implies RX.

> Double Transfer Rate uses the same wire.

But is it still on either the TX or RX signals?

> But as you sample at both the rising and the falling edges of the clock, this
> makes the cpha setting meaningless for such transfers, I think ;-)

Might affect what the first bit is possibly?

> However, as the future may bring us QDR, perhaps this should not be a
> boolean flag, but an integer value?
> Cfr. spi-tx-bus-width vs. the original spi-tx-dual/spi-tx-quad proposal.

> What would be a good name (as we only need one)? spi-data-phases?

Sounds reasonable, apart from the increasingly vague connection with
something that's recognizably SPI :P

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