Re: [PATCH] ARM: dts: imx28: add gpio-ranges for internal gpio controller

[Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>]

Hello Shawn,

On Mon, May 15, 2017 at 10:21:30AM +0800, Shawn Guo wrote:
> On Fri, May 12, 2017 at 10:01:50AM +0200, Uwe Kleine-König wrote:
> > On Fri, May 12, 2017 at 11:05:38AM +0800, Shawn Guo wrote:
> > > I went through the code around requesting a pin, and found that we need
> > > to call pinctrl_request_gpio() from gpio driver to get the result you
> > > want.  In that case, pin_request() will be called with a valid
> > > gpio_range as below.
> > > 
> > >     pinctrl_request_gpio()
> > >         pinmux_request_gpio()
> > >             pin_request(..., gpio_range)
> > > 
> > > Right now, pin_request() is being called with a NULL gpio_range from
> > > pinmux_enable_setting().  That gets us the mux_owner rather than
> > > gpio_owner for the pin.
> > 
> > But then again I cannot mux a pin to a different function when the gpio
> > is requested, right?

(Actually I intended to postpone this mail, but sent it instead by
accident.)
 
> You will need to free the GPIO before muxing it to a different function,
> I think.

IMHO this is a bad concept. This makes GPIOs more special than for
example PWMs or LEDs. And it breaks some configurations (for example the
make-pins-highz-on-idle setup in my previous mails).

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
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