Suspend to RAM¶

This state offers significant power savings as everything in the system is put into a low-power state, except for memory, which is placed into the self-refresh mode to retain its contents.

To suspend to RAM execute the following command:

# pm-suspend

Wake up¶

There are many possible ways to wake up from suspend.
A few examples:
- Pushing the ON/OFF button (when present on the board)

Pushing a button on the board which has the boolean property "wakeup-source" set in its device tree node (under gpio_keys), e.g.:

    gpio-keys {
        compatible = "gpio-keys";
        pinctrl-names = "default";
        pinctrl-0 = <&pinctrl_gpio_keys>;
               ...
               back {
                       label = "Back";
                       gpios = <&gpio4 6 GPIO_ACTIVE_LOW>;
                       linux,code = <KEY_BACK>;
                       wakeup-source;
               };
    };

Pressing the capacitive touch which has the "wakeup-source" property set in its device tree node, e.g.:

       ft5x06_ts: ft5x06_ts@38 {
               status = "disabled";
               compatible = "edt,edt-ft5x06";
               reg = <0x38>;
               reset-gpios = <&gpio4 5 GPIO_ACTIVE_LOW>;
               pinctrl-names = "default";
               pinctrl-0 = <&pinctrl_touch>;
               interrupt-parent = <&gpio1>;
               interrupts = <14 0>;
               touchscreen-size-x = <800>;
               touchscreen-size-y = <480>;
               touchscreen-inverted-x;
               touchscreen-inverted-y;
               wakeup-source;
       };

Measuring SOM current consumption in suspend¶

To measure the SOM current consumption remove resistor R15 on DT8MCustomBoard or R58 on Symphony-Board and connect an ammeter in its place.
It is recommended to boot from eMMC to get an accurate measurement.