Re: [PATCH v2 01/11] dt-bindings: spi: allow expressing DTR capability

Mark Brown
2020-02-27T16:44:29Z

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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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