[PATCH 10/10] spi: s3c64xx: add device tree support

[Thomas Abraham]

On 9 May 2012 22:32, Mark Brown <broonie at opensource.wolfsonmicro.com> wrote:
> On Wed, May 09, 2012 at 10:13:28PM +0800, Thomas Abraham wrote:
>> On 9 May 2012 17:07, Mark Brown <broonie at opensource.wolfsonmicro.com> wrote:
>> > On Wed, May 09, 2012 at 03:34:54AM +0530, Thomas Abraham wrote:
>
>> >> +- gpios: The gpio specifier for clock, mosi and miso interface lines (in no
>> >> +  particular order). The format of the gpio specifier depends on the gpio
>> >> +  controller.
>
>> > This seems odd...  This isn't a bitbanging controller, and surely the
>> > driver will need to know which signal is which?  I suspect this is
>> > actually for pinmux rather than to identify the signals but that should
>> > at least be made clear and really should be being done using the pinmux
>> > API.
>
>> The driver retrieves the list of gpio's that it is allowed to use. The
>> gpio numbers for miso, mosi and clk are mandatory but the order in
>> which they are specified is not important since the driver never needs
>> to which gpio is which interface line. I agree the pinmux api should
>> be used here, but the call to pinmux api would be a incremental change
>> here, not changing the code this patch is adding.
>
> I'd suggest just specifying the order - someone might want to use it
> later for some reason and it's not really a hardship for someone to use
> it.  Avoids any "how does that work?" questions like I had.

Ok. I will add the order of the gpios as you have suggested.

>
>> >> +  - samsung,spi-cs-gpio: A gpio specifier that specifies the gpio line used as
>> >> +    the slave select line by the spi controller. The format of the gpio
>> >> +    specifier depends on the gpio controller.
>
>> > We should really have a binding for this at the SPI level (and ideally
>> > some code to manage setting the GPIO too) - it's pretty common to use a
>> > GPIO as /CS.
>
>> The existing implementations vary in the way the nCS gpio lines are
>> specified. For some controllers, the nCS gpio's are included in the
>> spi device node whereas in this implementation, the nCS gpio is listed
>> in the spi slave device node.
>
> Yeah, I know.  I'm saying we should try to come up with a binding for
> this that can be used by new SPI contollers going forward so things are
> consistent.

Ok. For this patch series, I will continue with the samsung specific
binding for the nCS line.

Thanks,
Thomas.