On Mon, Mar 7, 2016 at 7:34 PM, Michael Hennerich
[off-list ref] wrote:

On 03/05/2016 03:32 PM, Jonathan Cameron wrote:

quoted

quoted

Changes since v2:
        * Use child nodes to describe channels
        * Fix probe return and driver remove path
        * Move locking closer to where its used
        * Remove WARN_ON but return error
        * Remove OPEN DRAIN configuration option

Why? I don't particularly mind as of course you aren't obliged to support
every option in a driver, but I'm curious ;)

I'm not aware that someone asked for that feature.
Supporting it the proper way requires a new GPIOF flag for gpiolib, which we
can still discuss later, in case someone asks for it.

We have:
include/dt-bindings/gpio/gpio.h

/*
 * Open Drain/Collector is the combination of single-ended active low,
 * Open Source/Emitter is the combination of single-ended active high.
 */
#define GPIO_OPEN_DRAIN (GPIO_SINGLE_ENDED | GPIO_ACTIVE_LOW)
#define GPIO_OPEN_SOURCE (GPIO_SINGLE_ENDED | GPIO_ACTIVE_HIGH)

So consumers can ask (in DT) for a line in open drain mode.

FLAG_OPEN_DRAIN will be set internally in gpiolibs gpio_desc
in of_find_gpio() as a result and it will behave as expected.

Yours,
Linus Walleij