iface-modem: don't rely on the cached current power state value

The real power state value of the modem may be changed by other means, e.g.
rfkill. So when changing power state of the modem in MM, we better recheck
which the current power status is.

A better full approach would be to follow rfkill changes, but this fix should
help until that is done.

https://bugzilla.gnome.org/show_bug.cgi?id=702838

src/mm-iface-modem.c

@@ -2983,7 +2983,8 @@ typedef struct {
     GSimpleAsyncResult *result;
     MmGdbusModem *skeleton;
     MMModemPowerState power_state;
-    MMModemPowerState previous_power_state;
+    MMModemPowerState previous_cached_power_state;
+    MMModemPowerState previous_real_power_state;
 } SetPowerStateContext;
 
 static void
@@ -3029,6 +3030,9 @@ modem_power_up_ready (MMIfaceModem *self,
 
     MM_IFACE_MODEM_GET_INTERFACE (self)->modem_power_up_finish (self, res, &error);
     if (error) {
+        /* If the real and cached ones are different, set the real one */
+        if (ctx->previous_cached_power_state != ctx->previous_real_power_state)
+            mm_gdbus_modem_set_power_state (ctx->skeleton, ctx->previous_real_power_state);
         g_simple_async_result_take_error (ctx->result, error);
         set_power_state_context_complete_and_free (ctx);
         return;
@@ -3060,9 +3064,12 @@ modem_power_down_ready (MMIfaceModem *self,
     GError *error = NULL;
 
     MM_IFACE_MODEM_GET_INTERFACE (self)->modem_power_down_finish (self, res, &error);
-    if (error)
+    if (error) {
+        /* If the real and cached ones are different, set the real one */
+        if (ctx->previous_cached_power_state != ctx->previous_real_power_state)
+            mm_gdbus_modem_set_power_state (ctx->skeleton, ctx->previous_real_power_state);
         g_simple_async_result_take_error (ctx->result, error);
-    else {
+    } else {
         mm_dbg ("Modem set in low-power mode...");
         mm_gdbus_modem_set_power_state (ctx->skeleton, ctx->power_state);
         g_simple_async_result_set_op_res_gboolean (ctx->result, TRUE);
@@ -3071,6 +3078,88 @@ modem_power_down_ready (MMIfaceModem *self,
     set_power_state_context_complete_and_free (ctx);
 }
 
+static void
+set_power_state (SetPowerStateContext *ctx)
+{
+    /* Already done if we're in the desired power state */
+    if (ctx->previous_real_power_state == ctx->power_state) {
+        mm_dbg ("No need to change power state: already in '%s' power state",
+                mm_modem_power_state_get_string (ctx->power_state));
+        /* If the real and cached ones are different, set the real one */
+        if (ctx->previous_cached_power_state != ctx->previous_real_power_state)
+            mm_gdbus_modem_set_power_state (ctx->skeleton, ctx->previous_real_power_state);
+        g_simple_async_result_set_op_res_gboolean (ctx->result, TRUE);
+        set_power_state_context_complete_and_free (ctx);
+        return;
+    }
+
+    /* Supported transitions:
+     * UNKNOWN|OFF|LOW --> ON
+     * ON --> LOW
+     */
+
+    /* Going into low power mode? */
+    if (ctx->power_state == MM_MODEM_POWER_STATE_LOW) {
+        /* Error if unsupported */
+        if (!MM_IFACE_MODEM_GET_INTERFACE (ctx->self)->modem_power_down ||
+            !MM_IFACE_MODEM_GET_INTERFACE (ctx->self)->modem_power_down_finish) {
+            g_simple_async_result_set_error (ctx->result,
+                                             MM_CORE_ERROR,
+                                             MM_CORE_ERROR_UNSUPPORTED,
+                                             "Going into low-power mode is not supported by this modem");
+            set_power_state_context_complete_and_free (ctx);
+            return;
+        }
+
+        MM_IFACE_MODEM_GET_INTERFACE (ctx->self)->modem_power_down (
+            MM_IFACE_MODEM (ctx->self),
+            (GAsyncReadyCallback)modem_power_down_ready,
+            ctx);
+        return;
+    }
+
+    /* Going out of low power mode? */
+    if (ctx->power_state == MM_MODEM_POWER_STATE_ON) {
+        /* Error if unsupported */
+        if (!MM_IFACE_MODEM_GET_INTERFACE (ctx->self)->modem_power_up ||
+            !MM_IFACE_MODEM_GET_INTERFACE (ctx->self)->modem_power_up_finish) {
+            g_simple_async_result_set_error (ctx->result,
+                                             MM_CORE_ERROR,
+                                             MM_CORE_ERROR_UNSUPPORTED,
+                                             "Going into full-power mode is not supported by this modem");
+            set_power_state_context_complete_and_free (ctx);
+            return;
+        }
+
+        MM_IFACE_MODEM_GET_INTERFACE (ctx->self)->modem_power_up (
+            MM_IFACE_MODEM (ctx->self),
+            (GAsyncReadyCallback)modem_power_up_ready,
+            ctx);
+        return;
+    }
+
+    g_assert_not_reached ();
+}
+
+static void
+set_power_state_load_ready (MMIfaceModem *self,
+                            GAsyncResult *res,
+                            SetPowerStateContext *ctx)
+{
+    GError *error = NULL;
+
+    ctx->previous_real_power_state = MM_IFACE_MODEM_GET_INTERFACE (self)->load_power_state_finish (self, res, &error);
+    if (error) {
+        g_debug ("Couldn't reload current power state: %s", error->message);
+        g_error_free (error);
+        /* Default to the cached one */
+        ctx->previous_real_power_state = ctx->previous_cached_power_state;
+    }
+
+    /* And keep on */
+    set_power_state (ctx);
+}
+
 void
 mm_iface_modem_set_power_state (MMIfaceModem *self,
                                 MMModemPowerState power_state,
@@ -3097,61 +3186,26 @@ mm_iface_modem_set_power_state (MMIfaceModem *self,
         set_power_state_context_complete_and_free (ctx);
         return;
     }
-    ctx->previous_power_state = mm_gdbus_modem_get_power_state (ctx->skeleton);
 
-    /* Already done if we're in the desired power state */
+    ctx->previous_cached_power_state = mm_gdbus_modem_get_power_state (ctx->skeleton);
-    if (ctx->previous_power_state == ctx->power_state) {
+
-        mm_dbg ("No need to change power state: already in '%s' power state",
+    /* We cannot really rely on the power state value that we had cached before,
-                mm_modem_power_state_get_string (ctx->power_state));
+     * as the real power status of the modem may also be changed by rfkill. So,
-        g_simple_async_result_set_op_res_gboolean (ctx->result, TRUE);
+     * before updating the current power state, re-check which is the real power
-        set_power_state_context_complete_and_free (ctx);
+     * state. */
+    if (MM_IFACE_MODEM_GET_INTERFACE (ctx->self)->load_power_state &&
+        MM_IFACE_MODEM_GET_INTERFACE (ctx->self)->load_power_state_finish) {
+        MM_IFACE_MODEM_GET_INTERFACE (ctx->self)->load_power_state (
+            ctx->self,
+            (GAsyncReadyCallback)set_power_state_load_ready,
+            ctx);
         return;
     }
 
-    /* Supported transitions:
+    /* If there is no way to load power state, just keep on assuming the cached
-     * UNKNOWN|OFF|LOW --> ON
+     * one is also the real one */
-     * ON --> LOW
+    ctx->previous_real_power_state = ctx->previous_cached_power_state;
-     */
+    set_power_state (ctx);
-
-    /* Going into low power mode? */
-    if (ctx->power_state == MM_MODEM_POWER_STATE_LOW) {
-        /* Error if unsupported */
-        if (!MM_IFACE_MODEM_GET_INTERFACE (self)->modem_power_down ||
-            !MM_IFACE_MODEM_GET_INTERFACE (self)->modem_power_down_finish) {
-            g_simple_async_result_set_error (ctx->result,
-                                             MM_CORE_ERROR,
-                                             MM_CORE_ERROR_UNSUPPORTED,
-                                             "Going into low-power mode is not supported by this modem");
-            set_power_state_context_complete_and_free (ctx);
-            return;
-        }
-
-        MM_IFACE_MODEM_GET_INTERFACE (self)->modem_power_down (MM_IFACE_MODEM (self),
-                                                               (GAsyncReadyCallback)modem_power_down_ready,
-                                                               ctx);
-        return;
-    }
-
-    /* Going out of low power mode? */
-    if (ctx->power_state == MM_MODEM_POWER_STATE_ON) {
-        /* Error if unsupported */
-        if (!MM_IFACE_MODEM_GET_INTERFACE (self)->modem_power_up ||
-            !MM_IFACE_MODEM_GET_INTERFACE (self)->modem_power_up_finish) {
-            g_simple_async_result_set_error (ctx->result,
-                                             MM_CORE_ERROR,
-                                             MM_CORE_ERROR_UNSUPPORTED,
-                                             "Going into full-power mode is not supported by this modem");
-            set_power_state_context_complete_and_free (ctx);
-            return;
-        }
-
-        MM_IFACE_MODEM_GET_INTERFACE (self)->modem_power_up (MM_IFACE_MODEM (self),
-                                                             (GAsyncReadyCallback)modem_power_up_ready,
-                                                             ctx);
-        return;
-    }
-
-    g_assert_not_reached ();
 }
 
 /*****************************************************************************/