oled ext pwr: Apply ddudek OLED ext pwr patch

This commit properly reinitializes the OLED display after ext power is re-enabled.

It requires a patch pn zephyr itself.

Until the patch is implemented in zephyr, it can be applied in your zmk-config’s github build action.

More info here:
zmkfirmware#674

Original code by ddudek can also be found in the above issue.

app/src/ext_power_generic.c

@@ -13,6 +13,9 @@
 #include <settings/settings.h>
 #include <drivers/gpio.h>
 #include <drivers/ext_power.h>
+#include <drivers/display.h>
+
+#define ZMK_DISPLAY_NAME CONFIG_LVGL_DISPLAY_DEV_NAME
 
 #include <zmk/activity.h>
 #include <zmk/usb.h>
@@ -64,6 +67,16 @@ int ext_power_save_state() {
 #endif
 }
 
+static void drivers_update_power_state(bool power) {
+    LOG_DBG("drivers_update_power_state: %s", power?"true":"false");
+    static const struct device *display;
+    display = device_get_binding(ZMK_DISPLAY_NAME);
+
+    if (display != NULL) {
+        display_update_ext_power(display, power);
+    }
+}
+
 static int ext_power_generic_enable(const struct device *dev) {
     struct ext_power_generic_data *data = dev->data;
     const struct ext_power_generic_config *config = dev->config;
@@ -73,6 +86,7 @@ static int ext_power_generic_enable(const struct device *dev) {
         return -EIO;
     }
     data->status = true;
+    drivers_update_power_state(true);
     return ext_power_save_state();
 }
 
@@ -85,6 +99,8 @@ static int ext_power_generic_disable(const struct device *dev) {
         return -EIO;
     }
     data->status = false;
+
+    drivers_update_power_state(false);
     return ext_power_save_state();
 }