monitor-manager-kms: Check if GPUs can have outputswip/laney/drmmodegetresources-handle-failure-2

We need a way for mutter to exit if no available GPUs are going to work.
For example if gdm starts gnome-shell and we're using a DRM driver that
doesn't work with KMS then we should exit so that GDM can try with Xorg,
rather than operating in headless mode.

Related: https://gitlab.gnome.org/GNOME/mutter/issues/223

3 files changed, 31 insertions, 1 deletions

diff --git a/src/backends/native/meta-gpu-kms.c b/src/backends/native/meta-gpu-kms.c
index 9de9fc63e..26203fb60 100644
--- a/src/backends/native/meta-gpu-kms.c
+++ b/src/backends/native/meta-gpu-kms.c
@@ -812,6 +812,22 @@ meta_gpu_kms_read_current (MetaGpu  *gpu,
   return TRUE;
 }
 
+gboolean
+meta_gpu_kms_can_have_outputs (MetaGpuKms *gpu_kms,
+                               GError     **error)
+{
+  if (gpu_kms->n_connectors == 0)
+    {
+      g_set_error (error,
+                   G_IO_ERROR,
+                   G_IO_ERROR_FAILED,
+                   "GPU has 0 usable connectors, can't use it");
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
 MetaGpuKms *
 meta_gpu_kms_new (MetaMonitorManagerKms  *monitor_manager_kms,
                   const char             *kms_file_path,
@@ -840,6 +856,8 @@ meta_gpu_kms_new (MetaMonitorManagerKms  *monitor_manager_kms,
 
   drmSetClientCap (gpu_kms->fd, DRM_CLIENT_CAP_UNIVERSAL_PLANES, 1);
 
+  meta_gpu_kms_read_current (META_GPU (gpu_kms), NULL);
+
   source = g_source_new (&kms_event_funcs, sizeof (MetaKmsSource));
   kms_source = (MetaKmsSource *) source;
   kms_source->fd_tag = g_source_add_unix_fd (source,
diff --git a/src/backends/native/meta-gpu-kms.h b/src/backends/native/meta-gpu-kms.h
index ef1f17ce8..d15b9435c 100644
--- a/src/backends/native/meta-gpu-kms.h
+++ b/src/backends/native/meta-gpu-kms.h
@@ -53,6 +53,9 @@ gboolean meta_gpu_kms_apply_crtc_mode (MetaGpuKms *gpu_kms,
                                        int         y,
                                        uint32_t    fb_id);
 
+gboolean meta_gpu_kms_can_have_outputs (MetaGpuKms *gpu_kms,
+                                        GError     **error);
+
 gboolean meta_gpu_kms_is_crtc_active (MetaGpuKms *gpu_kms,
                                       MetaCrtc   *crtc);
 
diff --git a/src/backends/native/meta-monitor-manager-kms.c b/src/backends/native/meta-monitor-manager-kms.c
index 6c7a87f01..df71d7e19 100644
--- a/src/backends/native/meta-monitor-manager-kms.c
+++ b/src/backends/native/meta-monitor-manager-kms.c
@@ -663,7 +663,8 @@ meta_monitor_manager_kms_initable_init (GInitable    *initable,
                                                primary_gpu_path,
                                                error);
   g_list_free_full (gpu_paths, g_free);
-  if (!manager_kms->primary_gpu)
+  if (!manager_kms->primary_gpu ||
+      !meta_gpu_kms_can_have_outputs (manager_kms->primary_gpu, error))
     return FALSE;
 
   meta_monitor_manager_kms_connect_uevent_handler (manager_kms);
@@ -686,6 +687,14 @@ meta_monitor_manager_kms_initable_init (GInitable    *initable,
           continue;
         }
 
+      if (!meta_gpu_kms_can_have_outputs (gpu_kms, &secondary_error))
+        {
+          g_warning ("Couldn't add secondary gpu '%s': %s",
+                     gpu_path, secondary_error->message);
+          g_clear_object (&gpu_kms);
+          continue;
+        }
+
       meta_monitor_manager_add_gpu (META_MONITOR_MANAGER (manager_kms),
                                     META_GPU (gpu_kms));
     }