monitor: Add flag whether EDID is sufficient to disambiguate monitors

If the EDID of the attached or stored monitor configurations contain
proper serial numbers, then we do not need to rely on the connector to
disambiguate them. Add a boolean to both MetaMonitorManager and
MetaMonitorsConfigKey to store this information.

https://gitlab.gnome.org/GNOME/mutter/issues/932

src/backends/meta-monitor-config-manager.c

@@ -410,6 +410,25 @@ is_lid_closed (MetaMonitorManager *monitor_manager)
     return meta_backend_is_lid_closed (backend);
 }
 
+gboolean
+meta_config_key_edid_sufficient_for_specs (GList *monitor_specs)
+{
+  GList *l;
+
+  for (l = monitor_specs; l && l->next; l = l->next)
+    {
+      MetaMonitorSpec *spec = l->data;
+      MetaMonitorSpec *spec_next = l->next->data;
+
+      if (meta_monitor_spec_equals (spec, spec_next, TRUE))
+        return FALSE;
+
+      /* XXX: Should we reject e.g. only 0 serial numbers? */
+    }
+
+  return TRUE;
+}
+
 MetaMonitorsConfigKey *
 meta_create_monitors_config_key_for_current_state (MetaMonitorManager *monitor_manager)
 {
@@ -439,7 +458,8 @@ meta_create_monitors_config_key_for_current_state (MetaMonitorManager *monitor_m
 
   config_key = g_new0 (MetaMonitorsConfigKey, 1);
   *config_key = (MetaMonitorsConfigKey) {
-    .monitor_specs = monitor_specs
+    .monitor_specs = monitor_specs,
+    .edid_sufficient = meta_config_key_edid_sufficient_for_specs (monitor_specs)
   };
 
   return config_key;
@@ -1356,7 +1376,8 @@ meta_monitors_config_key_new (GList *logical_monitor_configs,
 
   config_key = g_new0 (MetaMonitorsConfigKey, 1);
   *config_key = (MetaMonitorsConfigKey) {
-    .monitor_specs = monitor_specs
+    .monitor_specs = monitor_specs,
+    .edid_sufficient = meta_config_key_edid_sufficient_for_specs (monitor_specs)
   };
 
   return config_key;

src/backends/meta-monitor-config-manager.h

@@ -48,7 +48,9 @@ typedef struct _MetaLogicalMonitorConfig
 
 typedef struct _MetaMonitorsConfigKey
 {
+  /* monitor_specs needs to be sorted using meta_monitor_spec_compare. */
   GList *monitor_specs;
+  gboolean edid_sufficient;
 } MetaMonitorsConfigKey;
 
 typedef enum _MetaMonitorsConfigFlag
@@ -159,6 +161,9 @@ META_EXPORT_TEST
 gboolean meta_monitors_config_key_equal (gconstpointer config_key_a,
                                          gconstpointer config_key_b);
 
+META_EXPORT_TEST
+gboolean meta_config_key_edid_sufficient_for_specs (GList *monitor_specs);
+
 META_EXPORT_TEST
 void meta_monitors_config_key_free (MetaMonitorsConfigKey *config_key);
 

src/backends/meta-monitor-manager-private.h

@@ -122,6 +122,7 @@ struct _MetaMonitorManager
   int screen_height;
 
   GList *monitors;
+  gboolean edid_sufficient;
 
   GList *logical_monitors;
   MetaLogicalMonitor *primary_logical_monitor;

src/backends/meta-monitor-manager.c

@@ -2621,6 +2621,7 @@ rebuild_monitors (MetaMonitorManager *manager)
 {
   GList *gpus;
   GList *l;
+  GList *specs;
 
   if (manager->monitors)
     {
@@ -2659,6 +2660,15 @@ rebuild_monitors (MetaMonitorManager *manager)
             }
         }
     }
+
+  specs = NULL;
+  for (l = manager->monitors; l; l = l->next)
+    specs = g_list_prepend (specs, meta_monitor_get_spec (l->data));
+
+  specs = g_list_sort (specs,
+                       (GCompareFunc) meta_monitor_spec_compare);
+  manager->edid_sufficient = meta_config_key_edid_sufficient_for_specs (specs);
+  g_list_free (specs);
 }
 
 void

src/tests/monitor-store-unit-tests.c

@@ -108,7 +108,8 @@ create_config_key_from_expect (MonitorStoreTestConfiguration *expect_config)
 
   config_key = g_new0 (MetaMonitorsConfigKey, 1);
   *config_key = (MetaMonitorsConfigKey) {
-    .monitor_specs = monitor_specs
+    .monitor_specs = monitor_specs,
+    .edid_sufficient = meta_config_key_edid_sufficient_for_specs (monitor_specs)
   };
 
   return config_key;