On Wed, Mar 9, 2016 at 4:44 PM, Hans de Goede [off-list ref] wrote:

quoted

On Wed, Mar 09, 2016 at 01:17:50PM +0100, Hans de Goede wrote:

quoted

Eventually, yes, it needs both. But they don't even have to be the
same driver, since they provide two different features. The only
reason we have that construct in the pio case is because they share
the same address space, but in the AXP case, the regmap and our mfd
take care of that already.

Hmm, so your suggesting to have mfd instantiate 2 platform devices
for this, a gpio and a pinctrl device, each with their own
driver. Yes that would work, but I'm a bit worried about the 2
racing or some such since they both will end up touching
bit 0-2 of register 0x90 / 0x92, more-over since they are both
touching the exact same bits I've the feeling that this really
should be one driver.

We can put the driver in drivers/pinctrl/pinctrl-axp209.c from day
one, add in comments stating that it only implements GPIO
for now and that the GPIO portion must call
pinctrl_request_gpio() and the pin controller must implement
.gpio_request_enable() the day it is added so the GPIOs do
not conflict with other use of the pins.

Requireing a huge slew of upfront code is a bit hard on simple
drivers I think.

Also we have the solution in drivers/mfd/stmpe.c that just add
a simple mux code when pins on mixsigs or simple expanders
can just mux some two-three different functions, then I think
pin control may be a bit too thick overhead. (Not sure where
the limit is though.)

Yours,
Linus Walleij