Setting GPIO status during boot process

Question

I have an Intel Galileo board with LED connected to one of GPIO pin. When I am connecting power to Galileo, LED lights up for a second and then turns off again.

Once my application start I am able to manipulate LED. But now I want my LED to turned ON during whole boot process and once my application starts it should manipulate LED after then. I guess to achieve this I have to change kernel code and build it again completely.

Answer 1

If possible, you can make the default state of the GPIO high/low in Boot loader. Or, Refer the following Changes in linux kernel and device tree.

:arch/xxx/boot/dts/xxxx.dts

led@4 {
label = "evmsk:green:heartbeat";
gpios = <&gpio1 7 0>;
linux,default-trigger = "heartbeat";
default-state = "off";
};

:drivers/leds/leds-gpio.c

state = of_get_property(child, "default-state", NULL);
if (state) {
if (!strcmp(state, "keep"))
led.default_state = LEDS_GPIO_DEFSTATE_KEEP;
else if (!strcmp(state, "on"))
led.default_state = LEDS_GPIO_DEFSTATE_ON;
else
led.default_state = LEDS_GPIO_DEFSTATE_OFF;
}

ret = gpio_direction_output(led_dat->gpio, led_dat->active_low ^ state);