[battery-udev] Handle initial probe from idle callback

In some devices initial power supply device probing can block mce for
several seconds. As this happens during mce startup, it also delays
readiness of mce systemd service. Which in turn can cause unnecessary
waiting during bootup.

Handle time-consuming udev property scanning from idle callback so
that it happens after systemd has been notified that mce is ready.

Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

modules/battery-udev.c

@@ -1927,6 +1927,23 @@ udevtracker_event_cb(GIOChannel  *chn, GIOCondition cnd, gpointer aptr)
  * G_MODULE
  * ========================================================================= */
 
+static guint mcebat_init_tracker_id = 0;
+
+static gboolean
+mcebat_init_tracker_cb(gpointer aptr)
+{
+    (void)aptr;
+
+    udevtracker_object = udevtracker_create();
+
+    if( !udevtracker_start(udevtracker_object) )
+        goto EXIT;
+
+EXIT:
+    mcebat_init_tracker_id = 0;
+    return G_SOURCE_REMOVE;
+}
+
 /** Init function for the battery and charger module
  *
  * @param module (not used)
@@ -1940,16 +1957,15 @@ G_MODULE_EXPORT const gchar *g_module_check_init(GModule *module)
     udevdevice_init_blacklist();
     udevproperty_init_types();
 
-    udevtracker_object = udevtracker_create();
-
-    if( !udevtracker_start(udevtracker_object) )
-        goto EXIT;
-
     mcebat_dbus_init();
 
+    /* Initial udev probing can take a long time.
+     * Do it from idle callback in order not to delay
+     * reaching systemd unit ready state.
+     */
+    mcebat_init_tracker_id = g_idle_add(mcebat_init_tracker_cb, 0);
     mce_log(LL_DEBUG, "%s: loaded", MODULE_NAME);
 
-EXIT:
     return NULL;
 }
 
@@ -1961,6 +1977,9 @@ G_MODULE_EXPORT void g_module_unload(GModule *module)
 {
     (void)module;
 
+    if( mcebat_init_tracker_id )
+        g_source_remove(mcebat_init_tracker_id), mcebat_init_tracker_id = 0;
+
     mcebat_dbus_quit();
 
     udevtracker_delete(udevtracker_object), udevtracker_object = 0;