BBB - Yocto - Kirkstone - GPIO successful dts patch but gpio is not working

General Discussion
1

Hello,
I have problem making the gpios on BBB work. I prepare patch for the dts and apply it .
I think I have apply it successfully because when I check the “pins” file I get this.

$ cat /sys/kernel/debug/pinctrl/44e10800.pinmux-pinctrl-single/pins
pin 36 (PIN36) 2:gpio-32-63 44e10890 0000000f pinctrl-single 
pin 37 (PIN37) 3:gpio-32-63 44e10894 0000000f pinctrl-single

(it used to be 00000037 now its 0000000f)

I also added “gpioinfo” to my image by adding CORE_IMAGE_EXTRA_INSTALL += “libgpiod libgpiod-dev libgpiod-tools” to the recipe and now gpioinfo shows:

$ gpioinfo
gpiochip1 - 32 lines:
        line   2:       "P8_7"       unused  output  active-high 
        line   3:       "P8_8"       unused  output  active-high

I tried to control the pins in two ways

  1. using gpioset
    $ gpioset gpiochip1 2=1
  2. with /sys/clas/gpio
$ echo 66 > /sys/class/gpio/export
$ echo out > /sys/class/gpio/gpio66/direction
$ echo 0 > /sys/class/gpio/gpio66/value

However, neither one works.

These are details about my dts patch:

  1. linux-yocto/arch/arm/boot/dts/am335x-boneblack.dts - inside the file added
&am33xx_pinmux {
    pinctrl-names = "default";
    pinctrl-0 = <&gpio_pins>;

    status = "okay";  
};
  1. linux-yocto/arch/arm/boot/dts/am335x-bone-common.dtsi - inside the &am33xx_pinmux added
&am33xx_pinmux {
	pinctrl-names = "default";
	pinctrl-0 = <&clkout2_pin>;
.
.
	gpio_pins: pinmux_gpio_pins {
        pinctrl-single,pins = <
			AM33XX_PADCONF(AM335X_PIN_GPMC_ADVN_ALE, PIN_OUTPUT, MUX_MODE7)	/* gpio2_2 */
			AM33XX_PADCONF(AM335X_PIN_GPMC_OEN_REN, PIN_OUTPUT, MUX_MODE7)	/* gpio2_3 */			
        >;
    };
.
.
};

It seems that at some way the dts change that I patch is working. But this gpioinfo status “unused” bothers me.
I think that I’m missing something. Something else to enable the pgio pins.
Please help me.

2

Solution!

It turns out the the pins are mapped in wrong order.
instead of GPIO 66 i need to export GPIO 34.
I saw that in gpioinfo the gpiochips are swaped, but it turns out now that the
$gpioset gpiochip 12=0
command is not working at all.
Anyway I will investigate little bit more and will try to work in this way.

Note: This is he default way the pins are mapped when you download yocto, kirkstone and select beaglebone-yocto machine! I haven’t change nothing to get this problem!

3

You need to provide the specific gpiochip, i.e. gpioset gpiochip[0-3] 12=0

slr-