Re: [PATCH v6 2/4] pps: descriptor-based gpio, capture-clear addition

[Philipp Zabel]

Hi Tom,

On Tue, Nov 13, 2018 at 5:08 AM Tom Burkart <tom@xxxxxxxxxx> wrote:
>
> This patch changes the GPIO access for the pps-gpio driver from the
> integer based API to the descriptor based API.  It also adds
> documentation for the device tree capture-clear option and
> device tree capture-clear extraction.
>
> The change from integer based GPIO API to the descriptor based API
> breaks backward compatibility for the devicetree.  This is due to
> the descriptor based API appending "-gpio" or "-gpios" (see
> Documentation/gpio/base.txt.)

Documentation/devicetree/bindings/gpio/gpio.txt says:
 "While a non-existent <name> is considered valid
  for compatibility reasons (resolving to the "gpios" property),
  it is not allowed for new bindings."

This is not a new binding, so there should be no reason to change it.

gpiod_get() and friends support this by using the "gpios" property if
they are passed a NULL con_id.
of_find_gpio() in drivers/gpio/gpiolib-of.c contains the relevant code.

regards
Philipp