Re: [LINUX RFC v2 1/4] spi: add support of two chip selects & data stripe

From: Mark Brown
Date: Fri Sep 04 2015 - 11:38:11 EST

On Fri, Sep 04, 2015 at 02:35:52PM +0200, Martin Sperl wrote:
> > On 03.09.2015, at 14:12, Mark Brown <broonie@xxxxxxxxxx> wrote:

> > This isn't saying that the controller supports more than one chip, it's
> > saying that the controller supports asserting more than one chip select
> > at once which isn't the same thing. I'm also not entirely sure that
> > this makes sense as a separate feature to the data striping one - I'm
> > struggling to think of a way to use this sensibly separately to that.

> Well - there is one use-case that I can think of:
> fbtft has the requirement for some devices to control a GPIO to
> differentiate between command and data getting transferred
> - sort of 9 bit.

That's another thing again, isn't it? It's one device switching between
two different control interfaces at runtime rather than two devices
controlled in lockstep.

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