[mutter] monitor-config-manager: respect other outputs' CRTC

[Jonas Ådahl <jadahl src gnome org>]

commit 6975c8b4245acab029c019910c0966f62bc5665c
Author: Emilio Pozuelo Monfort <emilio pozuelo collabora co uk>
Date:   Mon Nov 12 19:46:06 2018 +0100

    monitor-config-manager: respect other outputs' CRTC
    
    We should not only take the old CRTC for an output whenever
    possible, but we should also assign one that is 'free', i.e.
    one that another monitor (to be processed after this one)
    isn't using, so that that monitor can use the same CRTC.
    
    https://gitlab.gnome.org/GNOME/mutter/issues/373

 src/backends/meta-monitor-config-manager.c | 78 ++++++++++++++++++++++++++++--
 1 file changed, 73 insertions(+), 5 deletions(-)
---
diff --git a/src/backends/meta-monitor-config-manager.c b/src/backends/meta-monitor-config-manager.c
index 335c3f34b..771c57fc1 100644
--- a/src/backends/meta-monitor-config-manager.c
+++ b/src/backends/meta-monitor-config-manager.c
@@ -76,6 +76,22 @@ meta_monitor_config_manager_get_store (MetaMonitorConfigManager *config_manager)
   return config_manager->config_store;
 }
 
+static gboolean
+is_crtc_reserved (MetaCrtc *crtc,
+                  GArray   *reserved_crtcs)
+{
+  unsigned int i;
+
+  for (i = 0; i < reserved_crtcs->len; i++)
+    {
+       glong id = g_array_index (reserved_crtcs, glong, i);
+       if (id == crtc->crtc_id)
+         return TRUE;
+    }
+
+  return FALSE;
+}
+
 static gboolean
 is_crtc_assigned (MetaCrtc  *crtc,
                   GPtrArray *crtc_infos)
@@ -95,7 +111,8 @@ is_crtc_assigned (MetaCrtc  *crtc,
 
 static MetaCrtc *
 find_unassigned_crtc (MetaOutput *output,
-                      GPtrArray  *crtc_infos)
+                      GPtrArray  *crtc_infos,
+                      GArray     *reserved_crtcs)
 {
   MetaCrtc *crtc;
   unsigned int i;
@@ -104,6 +121,21 @@ find_unassigned_crtc (MetaOutput *output,
   if (crtc && !is_crtc_assigned (crtc, crtc_infos))
     return crtc;
 
+  /* then try to assign a CRTC that wasn't used */
+  for (i = 0; i < output->n_possible_crtcs; i++)
+    {
+      crtc = output->possible_crtcs[i];
+
+      if (is_crtc_assigned (crtc, crtc_infos))
+        continue;
+
+      if (is_crtc_reserved (crtc, reserved_crtcs))
+        continue;
+
+      return crtc;
+    }
+
+  /* finally just give a CRTC that we haven't assigned */
   for (i = 0; i < output->n_possible_crtcs; i++)
     {
       crtc = output->possible_crtcs[i];
@@ -124,6 +156,7 @@ typedef struct
   MetaMonitorConfig *monitor_config;
   GPtrArray *crtc_infos;
   GPtrArray *output_infos;
+  GArray *reserved_crtcs;
 } MonitorAssignmentData;
 
 static gboolean
@@ -147,7 +180,8 @@ assign_monitor_crtc (MetaMonitor         *monitor,
 
   output = monitor_crtc_mode->output;
 
-  crtc = find_unassigned_crtc (output, data->crtc_infos);
+  crtc = find_unassigned_crtc (output, data->crtc_infos, data->reserved_crtcs);
+
   if (!crtc)
     {
       MetaMonitorSpec *monitor_spec = meta_monitor_get_spec (monitor);
@@ -229,6 +263,7 @@ assign_monitor_crtcs (MetaMonitorManager       *manager,
                       MetaMonitorConfig        *monitor_config,
                       GPtrArray                *crtc_infos,
                       GPtrArray                *output_infos,
+                      GArray                   *reserved_crtcs,
                       GError                  **error)
 {
   MetaMonitorSpec *monitor_spec = monitor_config->monitor_spec;
@@ -262,7 +297,8 @@ assign_monitor_crtcs (MetaMonitorManager       *manager,
     .logical_monitor_config = logical_monitor_config,
     .monitor_config = monitor_config,
     .crtc_infos = crtc_infos,
-    .output_infos = output_infos
+    .output_infos = output_infos,
+    .reserved_crtcs = reserved_crtcs
   };
   if (!meta_monitor_mode_foreach_crtc (monitor, monitor_mode,
                                        assign_monitor_crtc,
@@ -278,6 +314,7 @@ assign_logical_monitor_crtcs (MetaMonitorManager       *manager,
                               MetaLogicalMonitorConfig *logical_monitor_config,
                               GPtrArray                *crtc_infos,
                               GPtrArray                *output_infos,
+                              GArray                   *reserved_crtcs,
                               GError                  **error)
 {
   GList *l;
@@ -290,7 +327,7 @@ assign_logical_monitor_crtcs (MetaMonitorManager       *manager,
                                  logical_monitor_config,
                                  monitor_config,
                                  crtc_infos, output_infos,
-                                 error))
+                                 reserved_crtcs, error))
         return FALSE;
     }
 
@@ -306,12 +343,40 @@ meta_monitor_config_manager_assign (MetaMonitorManager *manager,
 {
   GPtrArray *crtc_infos;
   GPtrArray *output_infos;
+  GArray *reserved_crtcs;
   GList *l;
 
   crtc_infos =
     g_ptr_array_new_with_free_func ((GDestroyNotify) meta_crtc_info_free);
   output_infos =
     g_ptr_array_new_with_free_func ((GDestroyNotify) meta_output_info_free);
+  reserved_crtcs = g_array_new (FALSE, FALSE, sizeof (glong));
+
+  for (l = config->logical_monitor_configs; l; l = l->next)
+    {
+      MetaLogicalMonitorConfig *logical_monitor_config = l->data;
+      GList *k;
+
+      for (k = logical_monitor_config->monitor_configs; k; k = k->next)
+        {
+          MetaMonitorConfig *monitor_config = k->data;
+          MetaMonitorSpec *monitor_spec = monitor_config->monitor_spec;
+          MetaMonitor *monitor;
+          GList *o;
+
+          monitor = meta_monitor_manager_get_monitor_from_spec (manager, monitor_spec);
+
+          for (o = meta_monitor_get_outputs (monitor); o; o = o->next)
+            {
+              MetaOutput *output = o->data;
+              MetaCrtc *crtc;
+
+              crtc = meta_output_get_assigned_crtc (output);
+              if (crtc)
+                g_array_append_val (reserved_crtcs, crtc->crtc_id);
+            }
+        }
+    }
 
   for (l = config->logical_monitor_configs; l; l = l->next)
     {
@@ -319,14 +384,17 @@ meta_monitor_config_manager_assign (MetaMonitorManager *manager,
 
       if (!assign_logical_monitor_crtcs (manager, logical_monitor_config,
                                          crtc_infos, output_infos,
-                                         error))
+                                         reserved_crtcs, error))
         {
           g_ptr_array_free (crtc_infos, TRUE);
           g_ptr_array_free (output_infos, TRUE);
+          g_array_free (reserved_crtcs, TRUE);
           return FALSE;
         }
     }
 
+  g_array_free (reserved_crtcs, TRUE);
+
   *out_crtc_infos = crtc_infos;
   *out_output_infos = output_infos;