manager: make sure we don't reset the modem twice in a row

This patch adds a 3s delay when resetting the modem during which we 
avoid triggering a new reset. This makes sure we don't trigger a reset 
twice in a row.

It also disables any related running timer to avoid being re-triggered 
unnecessarily.

src/manager.c

@@ -110,10 +110,27 @@ void modem_configure(struct EG25Manager *manager)
     at_sequence_configure(manager);
 }
 
+static gboolean modem_reset_done(struct EG25Manager* manager)
+{
+    manager->modem_state = EG25_STATE_RESUMING;
+    manager->reset_timer = 0;
+    return FALSE;
+}
+
 void modem_reset(struct EG25Manager *manager)
 {
     int fd, ret, len = strlen(manager->modem_usb_id);
 
+    if (manager->reset_timer)
+        return;
+
+    if (manager->suspend_source) {
+        g_source_remove(manager->suspend_source);
+        manager->suspend_source = 0;
+    }
+
+    manager->modem_state = EG25_STATE_RESETTING;
+
     fd = open("/sys/bus/usb/drivers/usb/unbind", O_WRONLY);
     if (fd < 0)
         goto error;
@@ -127,16 +144,20 @@ void modem_reset(struct EG25Manager *manager)
         goto error;
     ret = write(fd, manager->modem_usb_id, len);
     if (ret < len)
-        g_warning("Couldn't unbind modem: wrote %d/%d bytes", ret, len);
-
+        g_warning("Couldn't bind modem: wrote %d/%d bytes", ret, len);
     close(fd);
 
+    /*
+     * 3s is long enough to make sure the modem has been bound back and
+     * short enough to ensure it hasn't been acquired by ModemManager
+     */
+    manager->reset_timer = g_timeout_add_seconds(3, G_SOURCE_FUNC(modem_reset_done), manager);
+
     return;
 
 error:
     // Everything else failed, reset the modem
     at_sequence_reset(manager);
-    manager->modem_state = EG25_STATE_RESETTING;
 }
 
 void modem_suspend(struct EG25Manager *manager)

src/manager.h

@@ -26,6 +26,11 @@ enum EG25State {
 
 struct EG25Manager {
     GMainLoop *loop;
+    guint reset_timer;
+
+    int at_fd;
+    guint at_source;
+    GList *at_cmds;
 
     enum EG25State modem_state;
     gchar *modem_usb_id;
@@ -40,10 +45,6 @@ struct EG25Manager {
     guint suspend_source;
 
 
-    int at_fd;
-    guint at_source;
-    GList *at_cmds;
-
     struct gpiod_chip *gpiochip[2];
     struct gpiod_line *gpio_out[5];
     struct gpiod_line *gpio_in[2];

src/mm-iface.c

@@ -35,7 +35,10 @@ static void add_modem(struct EG25Manager *manager, GDBusObject *object)
     g_assert(manager->mm_modem != NULL);
 
     if (manager->modem_state == EG25_STATE_RESUMING) {
+        if (manager->suspend_source) {
             g_source_remove(manager->suspend_source);
+            manager->suspend_source = 0;
+        }
         modem_resume_post(manager);
         manager->modem_state = EG25_STATE_CONFIGURED;
     }

src/suspend.c

@@ -20,6 +20,7 @@
 static gboolean check_modem_resume(struct EG25Manager *manager)
 {
     g_message("Modem wasn't probed in time, restart it!");
+    manager->suspend_source = 0;
     modem_reset(manager);
 
     return FALSE;