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

From: tom burkart
Date: Sat Nov 17 2018 - 06:24:25 EST


Quoting Philipp Zabel <philipp.zabel@xxxxxxxxx>:

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.

Hi Phillip,

Oops, sounds like I didn't read the documentation properly. Thanks for the clarification.
A new patch will be on its way shortly...

Tom