broadband-modem: new step during 'enabling_started' to initialize the modem

We previously had the modem initialization command merged with some other port
setup commands in the 'modem_init' step of the 'Modem' interface. Instead of
doing this, we now split the logic into two separate steps:

A first 'enabling_modem_init' modem initialization step is to be run just after
the ports have been opened, but only during the first enabling operation, and
only if the modem was not hotplugged. A hotplugged modem is assumed to be
properly initialized already, so no need to ATZ-it. Also, we will now wait 500ms
by default after the modem initialization command has been sent, to let it
settle down.

The second 'modem_init' step will be run during the 'Modem' interface
initialization, and it currently only holds specific setup of the primary and
secondary serial ports. We'll be modifying this logic a bit in the next commits,
so no big deal to have that step name unchanged.

7 files changed, 292 insertions, 245 deletions

diff --git a/plugins/iridium/mm-broadband-modem-iridium.c b/plugins/iridium/mm-broadband-modem-iridium.c
index fe88bc08..197a1f73 100644
--- a/plugins/iridium/mm-broadband-modem-iridium.c
+++ b/plugins/iridium/mm-broadband-modem-iridium.c
@@ -46,14 +46,6 @@ G_DEFINE_TYPE_EXTENDED (MMBroadbandModemIridium, mm_broadband_modem_iridium, MM_
 /*****************************************************************************/
 /* Initializing the modem (Modem interface) */
 
-static gboolean
-modem_init_finish (MMIfaceModem *self,
-                   GAsyncResult *res,
-                   GError **error)
-{
-    return !g_simple_async_result_propagate_error (G_SIMPLE_ASYNC_RESULT (res), error);
-}
-
 static const MMBaseModemAtCommand modem_init_sequence[] = {
     /* Init command */
     { "E0 V1", 3, FALSE, NULL },
@@ -61,58 +53,12 @@ static const MMBaseModemAtCommand modem_init_sequence[] = {
     { NULL }
 };
 
-static void
-init_sequence_ready (MMBroadbandModem *self,
-                     GAsyncResult *res,
-                     GSimpleAsyncResult *simple)
-{
-    GError *error = NULL;
-
-    mm_base_modem_at_sequence_finish (MM_BASE_MODEM (self), res, NULL, &error);
-    if (error)
-        g_simple_async_result_take_error (simple, error);
-    else
-        g_simple_async_result_set_op_res_gboolean (simple, TRUE);
-    g_simple_async_result_complete (simple);
-    g_object_unref (simple);
-}
-
 static gboolean
-after_atz_sleep_cb (GSimpleAsyncResult *simple)
-{
-    MMBaseModem *self;
-
-    self = MM_BASE_MODEM (g_async_result_get_source_object (G_ASYNC_RESULT (simple)));
-    /* Now, run the remaining sequence */
-    mm_base_modem_at_sequence (self,
-                               modem_init_sequence,
-                               NULL,  /* response_processor_context */
-                               NULL,  /* response_processor_context_free */
-                               (GAsyncReadyCallback)init_sequence_ready,
-                               simple);
-    g_object_unref (self);
-    return FALSE;
-}
-
-static void
-atz_ready (MMBroadbandModem *self,
-           GAsyncResult *res,
-           GSimpleAsyncResult *simple)
+modem_init_finish (MMIfaceModem *self,
+                   GAsyncResult *res,
+                   GError **error)
 {
-    GError *error = NULL;
-
-    mm_base_modem_at_command_finish (MM_BASE_MODEM (self), res, &error);
-    if (error) {
-        g_simple_async_result_take_error (simple, error);
-        g_simple_async_result_complete (simple);
-        g_object_unref (simple);
-        return;
-    }
-
-    /* Once ATZ reply is received, we need to wait a bit before going on,
-     * otherwise, the next commands given will receive garbage as reply
-     * (500ms should be enough) */
-    g_timeout_add (500, (GSourceFunc)after_atz_sleep_cb, simple);
+    return !!mm_base_modem_at_sequence_finish (MM_BASE_MODEM (self), res, NULL, error);
 }
 
 static void
@@ -120,19 +66,12 @@ modem_init (MMIfaceModem *self,
             GAsyncReadyCallback callback,
             gpointer user_data)
 {
-    GSimpleAsyncResult *result;
-
-    result = g_simple_async_result_new (G_OBJECT (self),
-                                        callback,
-                                        user_data,
-                                        modem_init);
-    /* First, send ATZ alone */
-    mm_base_modem_at_command (MM_BASE_MODEM (self),
-                              "Z",
-                              3,
-                              TRUE,
-                              (GAsyncReadyCallback)atz_ready,
-                              result);
+    mm_base_modem_at_sequence (MM_BASE_MODEM (self),
+                               modem_init_sequence,
+                               NULL,  /* response_processor_context */
+                               NULL,  /* response_processor_context_free */
+                               callback,
+                               user_data);
 }
 
 /*****************************************************************************/
diff --git a/plugins/mbm/mm-broadband-modem-mbm.c b/plugins/mbm/mm-broadband-modem-mbm.c
index a5738761..39648cf6 100644
--- a/plugins/mbm/mm-broadband-modem-mbm.c
+++ b/plugins/mbm/mm-broadband-modem-mbm.c
@@ -307,63 +307,93 @@ set_allowed_modes (MMIfaceModem *_self,
 /*****************************************************************************/
 /* Initializing the modem (Modem interface) */
 
+static gboolean
+modem_init_finish (MMIfaceModem *self,
+                   GAsyncResult *res,
+                   GError **error)
+{
+    /* Ignore errors */
+    mm_base_modem_at_command_full_finish (MM_BASE_MODEM (self), res, NULL);
+    return TRUE;
+}
+
+static void
+modem_init (MMIfaceModem *self,
+            GAsyncReadyCallback callback,
+            gpointer user_data)
+{
+    mm_base_modem_at_command_full (MM_BASE_MODEM (self),
+                                   mm_base_modem_peek_port_primary (MM_BASE_MODEM (self)),
+                                   "E0 V1 X4 &C1 +CMEE=1",
+                                   3,
+                                   FALSE,
+                                   FALSE,
+                                   NULL, /* cancellable */
+                                   callback,
+                                   user_data);
+}
+
+/*****************************************************************************/
+/* Initializing the modem (during first enabling) */
+
 typedef struct {
     GSimpleAsyncResult *result;
     MMBroadbandModemMbm *self;
-} ModemInitContext;
+} EnablingModemInitContext;
 
 static void
-modem_init_context_complete_and_free (ModemInitContext *ctx)
+enabling_modem_init_context_complete_and_free (EnablingModemInitContext *ctx)
 {
     g_simple_async_result_complete (ctx->result);
     g_object_unref (ctx->result);
     g_object_unref (ctx->self);
-    g_slice_free (ModemInitContext, ctx);
+    g_slice_free (EnablingModemInitContext, ctx);
 }
 
 static gboolean
-modem_init_finish (MMIfaceModem *self,
-                   GAsyncResult *res,
-                   GError **error)
+enabling_modem_init_finish (MMBroadbandModem *self,
+                            GAsyncResult *res,
+                            GError **error)
 {
-    /* Ignore errors */
-    mm_base_modem_at_sequence_finish (MM_BASE_MODEM (self), res, NULL, NULL);
-    return TRUE;
+    return !g_simple_async_result_propagate_error (G_SIMPLE_ASYNC_RESULT (res), error);
 }
 
 static void
-init_sequence_ready (MMBaseModem *self,
-                     GAsyncResult *res,
-                     ModemInitContext *ctx)
+enabling_init_sequence_ready (MMBaseModem *self,
+                              GAsyncResult *res,
+                              EnablingModemInitContext *ctx)
 {
-    mm_base_modem_at_sequence_finish (self, res, NULL, NULL);
+    /* Ignore errors */
+    mm_base_modem_at_sequence_full_finish (self, res, NULL, NULL);
     g_simple_async_result_set_op_res_gboolean (ctx->result, TRUE);
-    modem_init_context_complete_and_free (ctx);
+    enabling_modem_init_context_complete_and_free (ctx);
 }
 
-static const MMBaseModemAtCommand modem_init_sequence[] = {
+static const MMBaseModemAtCommand enabling_modem_init_sequence[] = {
     /* Init command */
-    { "&F E0 V1 X4 &C1 +CMEE=1", 3, FALSE, NULL },
+    { "&F", 3, FALSE, NULL },
     /* Ensure disconnected */
     { "*ENAP=0", 3, FALSE, NULL },
     { NULL }
 };
 
 static void
-run_init_sequence (ModemInitContext *ctx)
+run_enabling_init_sequence (EnablingModemInitContext *ctx)
 {
-    mm_base_modem_at_sequence (MM_BASE_MODEM (ctx->self),
-                               modem_init_sequence,
-                               NULL,  /* response_processor_context */
-                               NULL,  /* response_processor_context_free */
-                               (GAsyncReadyCallback)init_sequence_ready,
-                               ctx);
+    mm_base_modem_at_sequence_full (MM_BASE_MODEM (ctx->self),
+                                    mm_base_modem_peek_port_primary (MM_BASE_MODEM (ctx->self)),
+                                    enabling_modem_init_sequence,
+                                    NULL,  /* response_processor_context */
+                                    NULL,  /* response_processor_context_free */
+                                    NULL, /* cancellable */
+                                    (GAsyncReadyCallback)enabling_init_sequence_ready,
+                                    ctx);
 }
 
 static void
 emrdy_ready (MMBaseModem *self,
              GAsyncResult *res,
-             ModemInitContext *ctx)
+             EnablingModemInitContext *ctx)
 {
     GError *error = NULL;
 
@@ -386,26 +416,26 @@ emrdy_ready (MMBaseModem *self,
         g_error_free (error);
     }
 
-    run_init_sequence (ctx);
+    run_enabling_init_sequence (ctx);
 }
 
 static void
-modem_init (MMIfaceModem *self,
-            GAsyncReadyCallback callback,
-            gpointer user_data)
+enabling_modem_init (MMBroadbandModem *self,
+                     GAsyncReadyCallback callback,
+                     gpointer user_data)
 {
-    ModemInitContext *ctx;
+    EnablingModemInitContext *ctx;
 
-    ctx = g_slice_new0 (ModemInitContext);
+    ctx = g_slice_new0 (EnablingModemInitContext);
     ctx->result = g_simple_async_result_new (G_OBJECT (self),
                                              callback,
                                              user_data,
-                                             modem_init);
+                                             enabling_modem_init);
     ctx->self = g_object_ref (self);
 
     /* Modem is ready?, no need to check EMRDY */
     if (ctx->self->priv->have_emrdy) {
-        run_init_sequence (ctx);
+        run_enabling_init_sequence (ctx);
         return;
     }
 
@@ -1143,4 +1173,6 @@ mm_broadband_modem_mbm_class_init (MMBroadbandModemMbmClass *klass)
 
     object_class->finalize = finalize;
     broadband_modem_class->setup_ports = setup_ports;
+    broadband_modem_class->enabling_modem_init = enabling_modem_init;
+    broadband_modem_class->enabling_modem_init_finish = enabling_modem_init_finish;
 }
diff --git a/plugins/nokia/mm-broadband-modem-nokia.c b/plugins/nokia/mm-broadband-modem-nokia.c
index b70049ff..c169e1b4 100644
--- a/plugins/nokia/mm-broadband-modem-nokia.c
+++ b/plugins/nokia/mm-broadband-modem-nokia.c
@@ -114,18 +114,10 @@ modem_init_finish (MMIfaceModem *self,
 }
 
 static const MMBaseModemAtCommand modem_init_sequence[] = {
-    /* Send the init command twice; some devices (Nokia N900) appear to take a
-     * few commands before responding correctly.  Instead of penalizing them for
-     * being stupid the first time by failing to enable the device, just
-     * try again.
-     *
-     * TODO: only send init command 2nd time if 1st time failed?
-     *
-     * Also, when initializing a Nokia phone, first enable the echo,
+    /* Also, when initializing a Nokia phone, first enable the echo,
      * and then disable it, so that we get it properly disabled.
      */
-    { "Z E1 E0 V1", 3, FALSE, NULL },
-    { "Z E1 E0 V1", 3, FALSE, mm_base_modem_response_processor_no_result_continue },
+    { "E1 E0 V1", 3, FALSE, NULL },
 
     /* Setup errors */
     { "+CMEE=1", 3, FALSE, NULL },
@@ -150,6 +142,100 @@ modem_init (MMIfaceModem *self,
 }
 
 /*****************************************************************************/
+/* Initializing the modem (during first enabling) */
+
+typedef struct {
+    GSimpleAsyncResult *result;
+    MMBroadbandModemNokia *self;
+    guint retries;
+} EnablingModemInitContext;
+
+static void
+enabling_modem_init_context_complete_and_free (EnablingModemInitContext *ctx)
+{
+    g_simple_async_result_complete (ctx->result);
+    g_object_unref (ctx->result);
+    g_object_unref (ctx->self);
+    g_slice_free (EnablingModemInitContext, ctx);
+}
+
+static gboolean
+enabling_modem_init_finish (MMBroadbandModem *self,
+                            GAsyncResult *res,
+                            GError **error)
+
+{
+    return !g_simple_async_result_propagate_error (G_SIMPLE_ASYNC_RESULT (res), error);
+}
+
+static void retry_atz (EnablingModemInitContext *ctx);
+
+static void
+atz_ready (MMBaseModem *self,
+           GAsyncResult *res,
+           EnablingModemInitContext *ctx)
+{
+    GError *error = NULL;
+
+    /* One retry less */
+    ctx->retries--;
+
+    if (!mm_base_modem_at_command_full_finish (self, res, &error)) {
+        /* Consumed all retries... */
+        if (ctx->retries == 0) {
+            g_simple_async_result_take_error (ctx->result, error);
+            enabling_modem_init_context_complete_and_free (ctx);
+            return;
+        }
+
+        /* Retry... */
+        g_error_free (error);
+        retry_atz (ctx);
+        return;
+    }
+
+    /* Good! */
+    g_simple_async_result_set_op_res_gboolean (ctx->result, TRUE);
+    enabling_modem_init_context_complete_and_free (ctx);
+}
+
+static void
+retry_atz (EnablingModemInitContext *ctx)
+{
+    mm_base_modem_at_command_full (MM_BASE_MODEM (ctx->self),
+                                   mm_base_modem_peek_port_primary (MM_BASE_MODEM (ctx->self)),
+                                   "Z",
+                                   6,
+                                   FALSE,
+                                   FALSE,
+                                   NULL, /* cancellable */
+                                   (GAsyncReadyCallback)atz_ready,
+                                   ctx);
+}
+
+static void
+enabling_modem_init (MMBroadbandModem *self,
+                     GAsyncReadyCallback callback,
+                     gpointer user_data)
+{
+    EnablingModemInitContext *ctx;
+
+    ctx = g_slice_new0 (EnablingModemInitContext);
+    ctx->result = g_simple_async_result_new (G_OBJECT (self),
+                                             callback,
+                                             user_data,
+                                             enabling_modem_init);
+    ctx->self = g_object_ref (self);
+
+    /* Send the init command twice; some devices (Nokia N900) appear to take a
+     * few commands before responding correctly.  Instead of penalizing them for
+     * being stupid the first time by failing to enable the device, just
+     * try again. */
+    ctx->retries = 2;
+    retry_atz (ctx);
+}
+
+/*****************************************************************************/
 
 MMBroadbandModemNokia *
 mm_broadband_modem_nokia_new (const gchar *device,
@@ -214,4 +300,8 @@ iface_modem_init (MMIfaceModem *iface)
 static void
 mm_broadband_modem_nokia_class_init (MMBroadbandModemNokiaClass *klass)
 {
+    MMBroadbandModemClass *broadband_modem_class = MM_BROADBAND_MODEM_CLASS (klass);
+
+    broadband_modem_class->enabling_modem_init = enabling_modem_init;
+    broadband_modem_class->enabling_modem_init_finish = enabling_modem_init_finish;
 }
diff --git a/plugins/novatel/mm-broadband-modem-novatel-lte.c b/plugins/novatel/mm-broadband-modem-novatel-lte.c
index 9a21c4b2..0db16863 100644
--- a/plugins/novatel/mm-broadband-modem-novatel-lte.c
+++ b/plugins/novatel/mm-broadband-modem-novatel-lte.c
@@ -43,112 +43,6 @@ G_DEFINE_TYPE_EXTENDED (MMBroadbandModemNovatelLte, mm_broadband_modem_novatel_l
                         G_IMPLEMENT_INTERFACE (MM_TYPE_IFACE_MODEM_3GPP, iface_modem_3gpp_init));
 
 /*****************************************************************************/
-/* Initializing the modem (Modem interface) */
-
-static gboolean
-modem_init_finish (MMIfaceModem *self,
-                   GAsyncResult *res,
-                   GError **error)
-{
-    return !g_simple_async_result_propagate_error (G_SIMPLE_ASYNC_RESULT (res), error);
-}
-
-static void
-modem_init_sequence_ready (MMBaseModem *self,
-                           GAsyncResult *res,
-                           GSimpleAsyncResult *simple)
-{
-    GError *error = NULL;
-
-    mm_base_modem_at_sequence_full_finish (MM_BASE_MODEM (self), res, NULL, &error);
-    if (error)
-        g_simple_async_result_take_error (simple, error);
-    else {
-        MMAtSerialPort *secondary;
-
-        /* Disable echo in secondary port as well, if any */
-        secondary = mm_base_modem_peek_port_secondary (MM_BASE_MODEM (self));
-        if (secondary)
-            /* No need to wait for the reply */
-            mm_base_modem_at_command_full (MM_BASE_MODEM (self),
-                                           secondary,
-                                           "E0",
-                                           3,
-                                           FALSE,
-                                           FALSE, /* raw */
-                                           NULL, /* cancellable */
-                                           NULL,
-                                           NULL);
-
-        g_simple_async_result_set_op_res_gboolean (simple, TRUE);
-    }
-
-    g_simple_async_result_complete (simple);
-    g_object_unref (simple);
-}
-
-static const MMBaseModemAtCommand modem_init_sequence[] = {
-    /* Init command. ITU rec v.250 (6.1.1) says:
-     *   The DTE should not include additional commands on the same command line
-     *   after the Z command because such commands may be ignored.
-     * So run ATZ alone.
-     */
-    { "Z",       6, FALSE, mm_base_modem_response_processor_no_result_continue },
-
-    /* Ensure echo is off after the init command */
-    { "E0 V1",   3, FALSE, NULL },
-
-    /* Some phones (like Blackberries) don't support +CMEE=1, so make it
-     * optional.  It completely violates 3GPP TS 27.007 (9.1) but what can we do...
-     */
-    { "+CMEE=1", 3, FALSE, NULL },
-
-    /* Additional OPTIONAL initialization */
-    { "X4 &C1",  3, FALSE, NULL },
-
-    { NULL }
-};
-
-static void
-modem_init (MMIfaceModem *self,
-            GAsyncReadyCallback callback,
-            gpointer user_data)
-{
-    MMAtSerialPort *primary;
-    GSimpleAsyncResult *result;
-    guint init_sequence_index;
-
-    result = g_simple_async_result_new (G_OBJECT (self),
-                                        callback,
-                                        user_data,
-                                        modem_init);
-
-    primary = mm_base_modem_peek_port_primary (MM_BASE_MODEM (self));
-    if (!primary) {
-        g_simple_async_result_set_error (
-            result,
-            MM_CORE_ERROR,
-            MM_CORE_ERROR_FAILED,
-            "Need primary AT port to run modem init sequence");
-        g_simple_async_result_complete_in_idle (result);
-        g_object_unref (result);
-        return;
-    }
-
-    /* Skip ATZ if the device was hotplugged. */
-    init_sequence_index = mm_base_modem_get_hotplugged (MM_BASE_MODEM (self)) ? 1 : 0;
-
-    mm_base_modem_at_sequence_full (MM_BASE_MODEM (self),
-                                    primary,
-                                    &modem_init_sequence[init_sequence_index],
-                                    NULL,  /* response_processor_context */
-                                    NULL,  /* response_processor_context_free */
-                                    NULL, /* cancellable */
-                                    (GAsyncReadyCallback)modem_init_sequence_ready,
-                                    result);
-}
-
-/*****************************************************************************/
 /* Modem power down (Modem interface) */
 
 static gboolean
@@ -767,8 +661,6 @@ mm_broadband_modem_novatel_lte_init (MMBroadbandModemNovatelLte *self)
 static void
 iface_modem_init (MMIfaceModem *iface)
 {
-    iface->modem_init = modem_init;
-    iface->modem_init_finish = modem_init_finish;
     iface->modem_power_down = modem_power_down;
     iface->modem_power_down_finish = modem_power_down_finish;
     iface->create_bearer = modem_create_bearer;
diff --git a/src/mm-broadband-modem-qmi.c b/src/mm-broadband-modem-qmi.c
index f8b84d43..0606c8c4 100644
--- a/src/mm-broadband-modem-qmi.c
+++ b/src/mm-broadband-modem-qmi.c
@@ -7654,4 +7654,7 @@ mm_broadband_modem_qmi_class_init (MMBroadbandModemQmiClass *klass)
     broadband_modem_class->initialization_started_finish = initialization_started_finish;
     broadband_modem_class->enabling_started = enabling_started;
     broadband_modem_class->enabling_started_finish = enabling_started_finish;
+    /* Do not initialize the QMI modem through AT commands */
+    broadband_modem_class->enabling_modem_init = NULL;
+    broadband_modem_class->enabling_modem_init_finish = NULL;
 }
diff --git a/src/mm-broadband-modem.c b/src/mm-broadband-modem.c
index 12ed91b6..1057d166 100644
--- a/src/mm-broadband-modem.c
+++ b/src/mm-broadband-modem.c
@@ -107,6 +107,7 @@ typedef struct _PortsContext PortsContext;
 struct _MMBroadbandModemPrivate {
     /* Broadband modem specific implementation */
     PortsContext *enabled_ports_ctx;
+    gboolean modem_init_run;
 
     /*<--- Modem interface --->*/
     /* Properties */
@@ -2959,13 +2960,6 @@ modem_init_sequence_ready (MMBaseModem *self,
 }
 
 static const MMBaseModemAtCommand modem_init_sequence[] = {
-    /* Init command. ITU rec v.250 (6.1.1) says:
-     *   The DTE should not include additional commands on the same command line
-     *   after the Z command because such commands may be ignored.
-     * So run ATZ alone.
-     */
-    { "Z", 6, FALSE, mm_base_modem_response_processor_no_result_continue },
-
     /* Ensure echo is off after the init command */
     { "E0 V1",      3, FALSE, NULL },
 
@@ -7434,6 +7428,38 @@ disabling_stopped (MMBroadbandModem *self,
 }
 
 /*****************************************************************************/
+/* Initializing the modem (during first enabling) */
+
+static gboolean
+enabling_modem_init_finish (MMBroadbandModem *self,
+                            GAsyncResult *res,
+                            GError **error)
+{
+    return !!mm_base_modem_at_command_full_finish (MM_BASE_MODEM (self), res, error);
+}
+
+static void
+enabling_modem_init (MMBroadbandModem *self,
+                     GAsyncReadyCallback callback,
+                     gpointer user_data)
+{
+    /* Init command. ITU rec v.250 (6.1.1) says:
+     *   The DTE should not include additional commands on the same command line
+     *   after the Z command because such commands may be ignored.
+     * So run ATZ alone.
+     */
+    mm_base_modem_at_command_full (MM_BASE_MODEM (self),
+                                   mm_base_modem_peek_port_primary (MM_BASE_MODEM (self)),
+                                   "Z",
+                                   6,
+                                   FALSE,
+                                   FALSE,
+                                   NULL, /* cancellable */
+                                   callback,
+                                   user_data);
+}
+
+/*****************************************************************************/
 /* Enabling started */
 
 typedef struct {
@@ -7461,6 +7487,74 @@ enabling_started_finish (MMBroadbandModem *self,
 }
 
 static gboolean
+enabling_after_modem_init_timeout (EnablingStartedContext *ctx)
+{
+    /* Store enabled ports context and complete */
+    ctx->self->priv->enabled_ports_ctx = ports_context_ref (ctx->ports);
+    g_simple_async_result_set_op_res_gboolean (ctx->result, TRUE);
+    enabling_started_context_complete_and_free (ctx);
+    return FALSE;
+}
+
+static void
+enabling_modem_init_ready (MMBroadbandModem *self,
+                           GAsyncResult *res,
+                           EnablingStartedContext *ctx)
+{
+    GError *error = NULL;
+
+    if (!MM_BROADBAND_MODEM_GET_CLASS (ctx->self)->enabling_modem_init_finish (self, res, &error)) {
+        g_simple_async_result_take_error (ctx->result, error);
+        enabling_started_context_complete_and_free (ctx);
+        return;
+    }
+
+    /* Specify that the modem init was run once */
+    ctx->self->priv->modem_init_run = TRUE;
+
+    /* After the modem init sequence, give a 500ms period for the modem to settle */
+    mm_dbg ("Giving some time to settle the modem...");
+    g_timeout_add (500, (GSourceFunc)enabling_after_modem_init_timeout, ctx);
+}
+
+static void
+enabling_flash_done (MMSerialPort *port,
+                     GError *error,
+                     EnablingStartedContext *ctx)
+{
+    if (error) {
+        g_prefix_error (&error, "Primary port flashing failed: ");
+        g_simple_async_result_set_from_error (ctx->result, error);
+        enabling_started_context_complete_and_free (ctx);
+        return;
+    }
+
+    /* Skip modem initialization if the device was hotplugged OR if we already
+     * did it (i.e. don't reinitialize if the modem got disabled and enabled
+     * again) */
+    if (ctx->self->priv->modem_init_run)
+        mm_dbg ("Skipping modem initialization: not first enabling");
+    else if (mm_base_modem_get_hotplugged (MM_BASE_MODEM (ctx->self))) {
+        ctx->self->priv->modem_init_run = TRUE;
+        mm_dbg ("Skipping modem initialization: device hotplugged");
+    } else if (!MM_BROADBAND_MODEM_GET_CLASS (ctx->self)->enabling_modem_init ||
+             !MM_BROADBAND_MODEM_GET_CLASS (ctx->self)->enabling_modem_init_finish)
+        mm_dbg ("Skipping modem initialization: not required");
+    else {
+        mm_dbg ("Running modem initialization sequence...");
+        MM_BROADBAND_MODEM_GET_CLASS (ctx->self)->enabling_modem_init (ctx->self,
+                                                                       (GAsyncReadyCallback)enabling_modem_init_ready,
+                                                                       ctx);
+        return;
+    }
+
+    /* Store enabled ports context and complete */
+    ctx->self->priv->enabled_ports_ctx = ports_context_ref (ctx->ports);
+    g_simple_async_result_set_op_res_gboolean (ctx->result, TRUE);
+    enabling_started_context_complete_and_free (ctx);
+}
+
+static gboolean
 open_ports_enabling (MMBroadbandModem *self,
                      PortsContext *ctx,
                      GError **error)
@@ -7506,22 +7600,6 @@ open_ports_enabling (MMBroadbandModem *self,
 }
 
 static void
-enabling_flash_done (MMSerialPort *port,
-                     GError *error,
-                     EnablingStartedContext *ctx)
-{
-    if (error) {
-        g_prefix_error (&error, "Primary port flashing failed: ");
-        g_simple_async_result_set_from_error (ctx->result, error);
-    } else {
-        ctx->self->priv->enabled_ports_ctx = ports_context_ref (ctx->ports);
-        g_simple_async_result_set_op_res_gboolean (ctx->result, TRUE);
-    }
-
-    enabling_started_context_complete_and_free (ctx);
-}
-
-static void
 enabling_started (MMBroadbandModem *self,
                   GAsyncReadyCallback callback,
                   gpointer user_data)
@@ -7547,7 +7625,7 @@ enabling_started (MMBroadbandModem *self,
     }
 
     /* Ports were correctly opened, now flash the primary port */
-    mm_dbg ("Flashing primary port before enabling...");
+    mm_dbg ("Flashing primary AT port before enabling...");
     mm_serial_port_flash (MM_SERIAL_PORT (ctx->ports->primary),
                           100,
                           FALSE,
@@ -9284,6 +9362,8 @@ mm_broadband_modem_class_init (MMBroadbandModemClass *klass)
     klass->initialization_stopped = initialization_stopped;
     klass->enabling_started = enabling_started;
     klass->enabling_started_finish = enabling_started_finish;
+    klass->enabling_modem_init = enabling_modem_init;
+    klass->enabling_modem_init_finish = enabling_modem_init_finish;
     klass->disabling_stopped = disabling_stopped;
 
     g_object_class_override_property (object_class,
diff --git a/src/mm-broadband-modem.h b/src/mm-broadband-modem.h
index 481665ac..c3e33547 100644
--- a/src/mm-broadband-modem.h
+++ b/src/mm-broadband-modem.h
@@ -69,6 +69,17 @@ struct _MMBroadbandModemClass {
                                           GAsyncResult *res,
                                           GError **error);
 
+    /* Modem initialization. During the 'enabling' step, this setup will be
+     * called in order to initialize the modem, only if it wasn't hotplugged,
+     * as we assume that a hotplugged modem is already initialized. */
+    void     (* enabling_modem_init)        (MMBroadbandModem *self,
+                                             GAsyncReadyCallback callback,
+                                             gpointer user_data);
+    gboolean (* enabling_modem_init_finish) (MMBroadbandModem *self,
+                                             GAsyncResult *res,
+                                             GError **error);
+
+
     /* Last disabling step */
     gboolean (* disabling_stopped) (MMBroadbandModem *self,
                                     GError **error);