From db14e6099e437b64e7c691663f7218c69601f9d9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jonas=20=C3=85dahl?= <jadahl@gmail.com>
Date: Fri, 10 Mar 2017 16:29:11 +0800
Subject: [PATCH] monitor-manager-kms: Don't listen on hotplugs when paused

When mutter is paused (i.e. not the DRM master), stop listening on
hotplug events. Instead read the current state and set modes when
resumed.

This avoids a race condition in the drm API which currently only
manages to properly deal with one application querying the EDID state
at the same time when there are multiple mutter instances running at
the same time (e.g. gnome-shell driving gdm at the same time as
gnome-shell as the session instance).

https://bugzilla.gnome.org/show_bug.cgi?id=779837
---
 src/backends/native/meta-backend-native.c      | 16 +++++++++++++---
 src/backends/native/meta-monitor-manager-kms.c | 15 +++++++++++++++
 src/backends/native/meta-monitor-manager-kms.h |  4 ++++
 3 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/src/backends/native/meta-backend-native.c b/src/backends/native/meta-backend-native.c
index 22312d75f..3cd1d119d 100644
--- a/src/backends/native/meta-backend-native.c
+++ b/src/backends/native/meta-backend-native.c
@@ -537,21 +537,31 @@ meta_activate_session (void)
 void
 meta_backend_native_pause (MetaBackendNative *native)
 {
+  MetaBackend *backend = META_BACKEND (native);
+  MetaMonitorManager *monitor_manager =
+    meta_backend_get_monitor_manager (backend);
+  MetaMonitorManagerKms *monitor_manager_kms =
+    META_MONITOR_MANAGER_KMS (monitor_manager);
+
   clutter_evdev_release_devices ();
   clutter_egl_freeze_master_clock ();
+
+  meta_monitor_manager_kms_pause (monitor_manager_kms);
 }
 
 void meta_backend_native_resume (MetaBackendNative *native)
 {
   MetaBackend *backend = META_BACKEND (native);
-  MetaRenderer *renderer;
+  MetaMonitorManager *monitor_manager =
+    meta_backend_get_monitor_manager (backend);
+  MetaMonitorManagerKms *monitor_manager_kms =
+    META_MONITOR_MANAGER_KMS (monitor_manager);
   MetaCursorRenderer *cursor_renderer;
   MetaCursorRendererNative *cursor_renderer_native;
   ClutterActor *stage;
   MetaIdleMonitor *idle_monitor;
 
-  renderer = meta_backend_get_renderer (backend);
-  meta_renderer_native_queue_modes_reset (META_RENDERER_NATIVE (renderer));
+  meta_monitor_manager_kms_resume (monitor_manager_kms);
 
   clutter_evdev_reclaim_devices ();
   clutter_egl_thaw_master_clock ();
diff --git a/src/backends/native/meta-monitor-manager-kms.c b/src/backends/native/meta-monitor-manager-kms.c
index 3cedde118..5256b4775 100644
--- a/src/backends/native/meta-monitor-manager-kms.c
+++ b/src/backends/native/meta-monitor-manager-kms.c
@@ -1783,6 +1783,21 @@ meta_monitor_manager_kms_disconnect_uevent_handler (MetaMonitorManagerKms *manag
   manager_kms->uevent_handler_id = 0;
 }
 
+void
+meta_monitor_manager_kms_pause (MetaMonitorManagerKms *manager_kms)
+{
+  meta_monitor_manager_kms_disconnect_uevent_handler (manager_kms);
+}
+
+void
+meta_monitor_manager_kms_resume (MetaMonitorManagerKms *manager_kms)
+{
+  MetaMonitorManager *manager = META_MONITOR_MANAGER (manager_kms);
+
+  meta_monitor_manager_kms_connect_uevent_handler (manager_kms);
+  handle_hotplug_event (manager);
+}
+
 static void
 meta_monitor_manager_kms_init (MetaMonitorManagerKms *manager_kms)
 {
diff --git a/src/backends/native/meta-monitor-manager-kms.h b/src/backends/native/meta-monitor-manager-kms.h
index d4978b802..c641f28be 100644
--- a/src/backends/native/meta-monitor-manager-kms.h
+++ b/src/backends/native/meta-monitor-manager-kms.h
@@ -58,4 +58,8 @@ gboolean meta_monitor_manager_kms_flip_crtc (MetaMonitorManagerKms *manager_kms,
 
 void meta_monitor_manager_kms_wait_for_flip (MetaMonitorManagerKms *manager_kms);
 
+void meta_monitor_manager_kms_pause (MetaMonitorManagerKms *manager_kms);
+
+void meta_monitor_manager_kms_resume (MetaMonitorManagerKms *manager_kms);
+
 #endif /* META_MONITOR_MANAGER_KMS_H */