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

[Shawn Guo <shawnguo@kernel.org>]

On Thu, May 11, 2017 at 10:09:16AM +0200, Uwe Kleine-König wrote:
> On Thu, May 11, 2017 at 03:51:36PM +0800, Shawn Guo wrote:
> > On Mon, May 08, 2017 at 10:59:25AM +0200, Uwe Kleine-König wrote:
> > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> > > ---
> > > Hello,
> > > 
> > > with this patch applied I get the following lines in dmesg which looks
> > > fine:
> > > 
> > > 	[    0.227913] gpio gpiochip0: (80018000.pinctrl:gpio@0): created GPIO range 0->31 ==> 80018000.pinctrl PIN 0->31
> > > 	[    0.236100] gpio gpiochip1: (80018000.pinctrl:gpio@1): created GPIO range 0->31 ==> 80018000.pinctrl PIN 32->63
> > > 	[    0.244463] gpio gpiochip2: (80018000.pinctrl:gpio@2): created GPIO range 0->31 ==> 80018000.pinctrl PIN 64->95
> > > 	[    0.253020] gpio gpiochip3: (80018000.pinctrl:gpio@3): created GPIO range 0->31 ==> 80018000.pinctrl PIN 96->127
> > > 	[    0.261639] gpio gpiochip4: (80018000.pinctrl:gpio@4): created GPIO range 0->31 ==> 80018000.pinctrl PIN 128->159
> > > 
> > > But when looking at a used gpio
> > > 
> > > 	# cat /sys/kernel/debug/gpio
> > > 	gpiochip0: GPIOs 0-31, parent: platform/80018000.pinctrl:gpio@0, 80018000.pinctrl:gpio@0:
> > > 	...
> > > 	 gpio-20  (LED4                |?                   ) out hi
> > > 	...
> > > 
> > > 	# grep "pin 20 " /sys/kernel/debug/pinctrl/80018000.pinctrl/pinmux-pins
> > > 	pin 20 (GPMI_RDY0): leds (GPIO UNCLAIMED) function leds group leds.0
> > > 
> > > I wonder why there is still "GPIO UNCLAIMED". I would have expected that
> > > this disappears and somehow references the gpio_request issued by the
> > > led-gpio driver after my patch.
> > > 
> > > What am I missing?
> > 
> > It seems that's only the case where @strict of struct pinmux_ops is
> > true.  We should set it true for pinctrl-mxs, I guess?
> 
> The description is:
> 
>  * @strict: do not allow simultaneous use of the same pin for GPIO and another
>  *      function. Check both gpio_owner and mux_owner strictly before approving
>  *      the pin request.

Sorry, I misread the 'strict' code and my comment about it is
completely a noise.

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.

Shawn