Re: [PATCH 1/3] spi: add xtfpga SPI controller driver

[Mark Brown]

On Wed, Mar 12, 2014 at 05:43:49AM +0400, Max Filippov wrote:
> On Wed, Mar 12, 2014 at 5:08 AM, Mark Brown <broonie@xxxxxxxxxx> wrote:

> > That's buggy, drivers should never configure anything more than 8 bits
> > per word with regmap.

> Ok, so the driver should allow for 8 bit transfers and regmap will arrange
> transfers as 8-bit pairs, making CS to be asserted for 16 bits, right?

> Hmmm... I see the only way to support that with that hardware: advertise
> 8 bit support, buffer bytes up to 16 bits, send 16 bit words on CS deassertion
> request, log violations verbosely. Other ideas?

That's about it.  Like I keep saying for any sort of generic use you
really want to support 8 bits per word.

> > You're missing the point.  The controller chip select line can do what
> > it likes, it's not connected to the target device if a GPIO is being
> > used.

> In my case SPI controller is wired directly to the codec with three
> wires: SDIN, SCLK and CS. There are no registers that can control
> either of these wires independently of others.

Right, but other users are likely to exist and the framework has support
for this so it's not much work to support.

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