On Mon, Oct 6, 2014 at 5:39 PM, Yegor Yefremov yegorslists@googlemail.com wrote:

U-Boot 2014.07

I'm trying to use ping 44..47 as input. I've configured PINMUX and invoked request, direction etc. I always get 0 from gpio_get_value()

    int val;

    gpio_request(44, "dip_s1"):
    gpio_request(45, "dip_s2");
    gpio_request(46, "dip_s3");
    gpio_request(47, "dip_s4");

    gpio_direction_input(44);
    gpio_direction_input(45);
    gpio_direction_input(46);
    gpio_direction_input(47);

    val = gpio_get_value(44);
    printf("DIP value: %d\n", val);
    val = gpio_get_value(45);
    printf("DIP value: %d\n", val);
    val = gpio_get_value(46);
    printf("DIP value: %d\n", val);
    val = gpio_get_value(47);
    printf("DIP value: %d\n", val);

After reading http://e2e.ti.com/support/arm/sitara_arm/f/791/t/248181.aspx I've checked clock registers CM_PER_L4LS_CLKSTCTRL (bit 8 L4LS_GCLK is set) and also CM_PER_GPIO1_CLKCTRL has value 2 - enabled. I can also see, that arch/arm/cpu/armv7/am33xx/clock_am33xx.c->enable_basic_clocks() enables clocks for GPIO1.

Then I checked GPIO1 specific registers and found out, that GPIO_SYSSTATUS (0x4804C114) shows 0x00000000 i.e. GPIO is still in reset. Any idea, what should be activated/setup in order to get the second GPIO bank working?

Some more details. These pins are working in Linux. In U-boot I can use them as output via "gpio toggle 44" (I can measure the signal via oscilloscope). So the requirements, that were mentioned in the thread on TI forum are met. I still cannot understand from TRM, if debounce clock is necessary or optional in order to get input working?

Yegor