[mutter] renderer-native: Fake page flipped if power saving when retrying

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 53b59d8bff05dee84fc8459794696776b971fa77
Author: Jonas Ådahl <jadahl gmail com>
Date:   Mon Mar 25 10:19:21 2019 +0100

    renderer-native: Fake page flipped if power saving when retrying
    
    When we're in a page-flip retry loop due to the FIFO being full
    (drmModePageFlip() failing with EBUSY), we should not continue to try
    when starting to power save, as that means we're blocking new frames,
    which itself blocks input events due to them being compressed using the
    frame clock.
    
    We'd also hit an assert assuming we only try to page flip when not power
    saving.
    
    Thus, fake we flipped if we ended up reaching a power saving state while
    retrying.
    
    Fixes: https://gitlab.gnome.org/GNOME/mutter/issues/509
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/506

 src/backends/native/meta-renderer-native.c | 51 +++++++++++++++++++++++-------
 1 file changed, 40 insertions(+), 11 deletions(-)
---
diff --git a/src/backends/native/meta-renderer-native.c b/src/backends/native/meta-renderer-native.c
index d0de9d0d0..e550a47e7 100644
--- a/src/backends/native/meta-renderer-native.c
+++ b/src/backends/native/meta-renderer-native.c
@@ -1541,14 +1541,39 @@ retry_page_flip_data_free (RetryPageFlipData *retry_page_flip_data)
   g_free (retry_page_flip_data);
 }
 
+static void
+retry_page_flip_data_fake_flipped (RetryPageFlipData  *retry_page_flip_data,
+                                   MetaOnscreenNative *onscreen_native)
+{
+  MetaCrtc *crtc = retry_page_flip_data->crtc;
+  MetaGpuKms *gpu_kms = META_GPU_KMS (meta_crtc_get_gpu (crtc));
+
+  if (gpu_kms != onscreen_native->render_gpu)
+    {
+      MetaOnscreenNativeSecondaryGpuState *secondary_gpu_state;
+
+      secondary_gpu_state =
+        meta_onscreen_native_get_secondary_gpu_state (onscreen_native,
+                                                      gpu_kms);
+      secondary_gpu_state->pending_flips--;
+    }
+
+  onscreen_native->total_pending_flips--;
+}
+
 static gboolean
 retry_page_flips (gpointer user_data)
 {
   MetaOnscreenNative *onscreen_native = user_data;
+  MetaRendererNative *renderer_native = onscreen_native->renderer_native;
+  MetaMonitorManager *monitor_manager =
+    META_MONITOR_MANAGER (renderer_native->monitor_manager_kms);
   uint64_t now_us;
+  MetaPowerSave power_save_mode;
   GList *l;
 
   now_us = g_source_get_time (onscreen_native->retry_page_flips_source);
+  power_save_mode = meta_monitor_manager_get_power_save_mode (monitor_manager);
 
   l = onscreen_native->pending_page_flip_retries;
   while (l)
@@ -1560,6 +1585,19 @@ retry_page_flips (gpointer user_data)
       g_autoptr (GError) error = NULL;
       gboolean did_flip;
 
+      if (power_save_mode != META_POWER_SAVE_ON)
+        {
+          onscreen_native->pending_page_flip_retries =
+            g_list_remove_link (onscreen_native->pending_page_flip_retries, l);
+
+          retry_page_flip_data_fake_flipped (retry_page_flip_data,
+                                             onscreen_native);
+          retry_page_flip_data_free (retry_page_flip_data);
+
+          l = l_next;
+          continue;
+        }
+
       if (is_timestamp_earlier_than (now_us,
                                      retry_page_flip_data->retry_time_us))
         {
@@ -1591,17 +1629,8 @@ retry_page_flips (gpointer user_data)
                                 G_IO_ERROR_PERMISSION_DENIED))
             g_critical ("Failed to page flip: %s", error->message);
 
-          if (gpu_kms != onscreen_native->render_gpu)
-            {
-              MetaOnscreenNativeSecondaryGpuState *secondary_gpu_state;
-
-              secondary_gpu_state =
-                meta_onscreen_native_get_secondary_gpu_state (onscreen_native,
-                                                              gpu_kms);
-              secondary_gpu_state->pending_flips--;
-            }
-
-          onscreen_native->total_pending_flips--;
+          retry_page_flip_data_fake_flipped (retry_page_flip_data,
+                                             onscreen_native);
         }
 
       retry_page_flip_data_free (retry_page_flip_data);