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

From: Martin Sperl
Date: Fri Sep 04 2015 - 11:49:09 EST

> On 04.09.2015, at 17:37, Mark Brown <broonie@xxxxxxxxxx> wrote:
> 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.

I agree, but there may be a solution that can handle both, so I wanted
to mention it.
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