[display] Expose blanking pause allowed -policy on dbus. JB#41340

Whether blanking pause is allowed or not depends on many variables.
Which makes it difficult for clients to know when they can expect
blanking pause requests they make to have any effect.

Expose the policy decision made within mce on D-Bus - so that:
- clients can track just one boolean state
- no changes are needed later on even if the policy should change

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

mce.conf

@@ -115,6 +115,9 @@
 		<allow send_destination="com.nokia.mce"
 		       send_interface="com.nokia.mce.request"
 		       send_member="req_display_cancel_blanking_pause"/>
+		<allow send_destination="com.nokia.mce"
+		       send_interface="com.nokia.mce.request"
+		       send_member="get_display_blanking_pause_allowed"/>
 		<allow send_destination="com.nokia.mce"
 		       send_interface="com.nokia.mce.request"
 		       send_member="get_display_blanking_inhibit"/>

modules/display.c

@@ -846,7 +846,9 @@ static void                mdy_governor_setting_cb(GConfClient *const client, co
  * ------------------------------------------------------------------------- */
 
 static gboolean            mdy_dbus_send_blanking_pause_status(DBusMessage *const method_call);
+static gboolean            mdy_dbus_send_blanking_pause_allowed_status(DBusMessage *const method_call);
 static gboolean            mdy_dbus_handle_blanking_pause_get_req(DBusMessage *const msg);
+static gboolean            mdy_dbus_handle_blanking_pause_allowed_get_req(DBusMessage *const msg);
 
 static gboolean            mdy_dbus_send_blanking_inhibit_status(DBusMessage *const method_call);
 static gboolean            mdy_dbus_handle_blanking_inhibit_get_req(DBusMessage *const msg);
@@ -4109,6 +4111,8 @@ static void mdy_blanking_pause_evaluate_allowed(void)
 
         if( blanking_pause_allowed != TRISTATE_TRUE )
             mdy_blanking_remove_pause_clients();
+
+        mdy_dbus_send_blanking_pause_allowed_status(0);
     }
 }
 
@@ -8729,6 +8733,50 @@ static gboolean mdy_dbus_send_blanking_pause_status(DBusMessage *const method_ca
     return TRUE;
 }
 
+/** Send a blanking pause allowed reply or signal
+ *
+ * @param method_call A DBusMessage to reply to; or NULL to send signal
+ *
+ * @return TRUE
+ */
+static gboolean mdy_dbus_send_blanking_pause_allowed_status(DBusMessage *const method_call)
+{
+    static int   prev = -1;
+    bool         curr = blanking_pause_allowed;
+    dbus_bool_t  data = curr;
+    DBusMessage *msg  = 0;
+
+    if( method_call ) {
+        msg = dbus_new_method_reply(method_call);
+        mce_log(LL_DEBUG, "Sending blanking pause allowed reply: %s",
+                data ? "true" : "false");
+    }
+    else if( prev == curr ) {
+        /* Omit no-change signals */
+        goto EXIT;
+    }
+    else {
+        prev = curr;
+        msg = dbus_new_signal(MCE_SIGNAL_PATH, MCE_SIGNAL_IF,
+                              MCE_PREVENT_BLANK_ALLOWED_SIG);
+        mce_log(LL_DEVEL, "Sending blanking pause allowed signal: %s",
+                data ? "true" : "false");
+    }
+
+    if( !dbus_message_append_args(msg,
+                                  DBUS_TYPE_BOOLEAN, &data,
+                                  DBUS_TYPE_INVALID) )
+        goto EXIT;
+
+    dbus_send_message(msg), msg = 0;
+
+EXIT:
+    if( msg )
+        dbus_message_unref(msg);
+
+    return TRUE;
+}
+
 /** D-Bus callback for the get blanking pause status method call
  *
  * @param msg The D-Bus message
@@ -8745,6 +8793,22 @@ static gboolean mdy_dbus_handle_blanking_pause_get_req(DBusMessage *const msg)
     return TRUE;
 }
 
+/** D-Bus callback for the get blanking pause allowed method call
+ *
+ * @param msg The D-Bus message
+ *
+ * @return TRUE
+ */
+static gboolean mdy_dbus_handle_blanking_pause_allowed_get_req(DBusMessage *const msg)
+{
+    mce_log(LL_DEVEL, "Received blanking pause allowed get request from %s",
+            mce_dbus_get_message_sender_ident(msg));
+
+    mdy_dbus_send_blanking_pause_allowed_status(msg);
+
+    return TRUE;
+}
+
 /** Send a blanking inhibit status reply or signal
  *
  * @param method_call A DBusMessage to reply to; or NULL to send signal
@@ -9624,6 +9688,13 @@ static mce_dbus_handler_t mdy_dbus_handlers[] =
         .args      =
             "    <arg name=\"blanking_pause\" type=\"s\"/>\n"
     },
+    {
+        .interface = MCE_SIGNAL_IF,
+        .name      = MCE_PREVENT_BLANK_ALLOWED_SIG,
+        .type      = DBUS_MESSAGE_TYPE_SIGNAL,
+        .args      =
+            "    <arg name=\"allowed\" type=\"b\"/>\n"
+    },
     {
         .interface = MCE_SIGNAL_IF,
         .name      = MCE_BLANKING_INHIBIT_SIG,
@@ -9668,6 +9739,14 @@ static mce_dbus_handler_t mdy_dbus_handlers[] =
         .args      =
             "    <arg direction=\"out\" name=\"blanking_pause\" type=\"s\"/>\n"
     },
+    {
+        .interface = MCE_REQUEST_IF,
+        .name      = MCE_PREVENT_BLANK_ALLOWED_GET,
+        .type      = DBUS_MESSAGE_TYPE_METHOD_CALL,
+        .callback  = mdy_dbus_handle_blanking_pause_allowed_get_req,
+        .args      =
+            "    <arg direction=\"out\" name=\"allowed\" type=\"b\"/>\n"
+    },
     {
         .interface = MCE_REQUEST_IF,
         .name      = MCE_BLANKING_INHIBIT_GET,

rpm/mce.spec

@@ -19,7 +19,7 @@ BuildRequires:  pkgconfig(dbus-glib-1)
 BuildRequires:  pkgconfig(dsme) >= 0.58
 BuildRequires:  pkgconfig(libiphb)
 BuildRequires:  pkgconfig(glib-2.0) >= 2.36.0
-BuildRequires:  pkgconfig(mce) >= 1.24.0
+BuildRequires:  pkgconfig(mce) >= 1.25.0
 BuildRequires:  pkgconfig(libngf0) >= 0.24
 BuildRequires:  pkgconfig(libsystemd-daemon)
 BuildRequires:  kernel-headers >= 2.6.32