On Fri, Jul 4, 2014 at 2:28 PM, Linus Walleij [off-list ref] wrote:

On Mon, Jun 30, 2014 at 2:53 PM, Mark Rutland [off-list ref] wrote:

quoted

On Thu, Jun 26, 2014 at 11:59:46PM +0100, Feng Kan wrote:

quoted

quoted

+- #gpio-cells: Should be two.
+     - first cell is the pin number
+     - second cell is used to specify optional parameters (unused)

Why is there an unused cell?

Why not just make this a single cell if the binding defines no valid
parameters?

I don't get this either. The only reason would be that this cell
should contain flags (such as open collector) the code for using
it being inplemented later.

Yes, open drain configuration and mux via pinctrl was something I
planned for later.
There was another reason for this as well, part of the gpio code I read
was confusing me. So I look through the other gpio documentations and
found an example that did this as well.

int of_gpio_simple_xlate(struct gpio_chip *gc,
                         const struct of_phandle_args *gpiospec, u32 *flags)
{
        /*
         * We're discouraging gpio_cells < 2, since that way you'll have to
         * write your own xlate function (that will have to retrive the GPIO
         * number and the flags from a single gpio cell -- this is possible,
         * but not recommended).
         */

Thanks, and please advise me on what to do next.

If the controller is too primitive to use such flags it should be onecell.

Yours,
Linus Walleij