From 86000c32d64cea7be2e6ed911cb9ea5df1306c0e Mon Sep 17 00:00:00 2001
From: Mario Limonciello <mario.limonciello@amd.com>
Date: Thu, 18 Aug 2022 13:36:20 -0500
Subject: [PATCH 1/2] output/kms: Add more heuristics to decide when to offer
 fallback modes

If the panel is connected via eDP and supports more than one mode
at different resolutions don't try to add more.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2586>
(cherry picked from commit 96aa0fb8536eca579ceb1b17d83e19cf9e3e9e81)
(cherry picked from commit 877cc3eb7d44e2886395151f763ec09bea350444)
---
 src/backends/native/meta-output-kms.c | 56 +++++++++++++++++++++------
 1 file changed, 44 insertions(+), 12 deletions(-)

diff --git a/src/backends/native/meta-output-kms.c b/src/backends/native/meta-output-kms.c
index f35cdf04e1..9adc20bfd9 100644
--- a/src/backends/native/meta-output-kms.c
+++ b/src/backends/native/meta-output-kms.c
@@ -224,6 +224,45 @@ compare_modes (const void *one,
                     meta_crtc_mode_get_name (crtc_mode_two));
 }
 
+static gboolean
+are_all_modes_equally_sized (MetaOutputInfo *output_info)
+{
+  const MetaCrtcModeInfo *base =
+    meta_crtc_mode_get_info (output_info->modes[0]);
+  int i;
+
+  for (i = 1; i < output_info->n_modes; i++)
+    {
+      const MetaCrtcModeInfo *mode_info =
+        meta_crtc_mode_get_info (output_info->modes[i]);
+
+      if (base->width != mode_info->width ||
+          base->height != mode_info->height)
+        return FALSE;
+    }
+
+  return TRUE;
+}
+
+static void
+maybe_add_fallback_modes (const MetaKmsConnectorState *connector_state,
+                          MetaOutputInfo              *output_info,
+                          MetaGpuKms                  *gpu_kms,
+                          MetaKmsConnector            *kms_connector)
+{
+  if (!connector_state->has_scaling)
+    return;
+
+  if (output_info->connector_type == DRM_MODE_CONNECTOR_eDP &&
+      !are_all_modes_equally_sized (output_info))
+    return;
+
+  meta_topic (META_DEBUG_KMS, "Adding common modes to connector %u on %s",
+              meta_kms_connector_get_id (kms_connector),
+              meta_gpu_kms_get_file_path (gpu_kms));
+  add_common_modes (output_info, gpu_kms);
+}
+
 static gboolean
 init_output_modes (MetaOutputInfo    *output_info,
                    MetaGpuKms        *gpu_kms,
@@ -252,14 +291,7 @@ init_output_modes (MetaOutputInfo    *output_info,
         output_info->preferred_mode = output_info->modes[i];
     }
 
-  if (connector_state->has_scaling)
-    {
-      meta_topic (META_DEBUG_KMS, "Adding common modes to connector %u on %s",
-                  meta_kms_connector_get_id (kms_connector),
-                  meta_gpu_kms_get_file_path (gpu_kms));
-      add_common_modes (output_info, gpu_kms);
-    }
-
+  maybe_add_fallback_modes (connector_state, output_info, gpu_kms, kms_connector);
   if (!output_info->modes)
     {
       g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
@@ -322,6 +354,10 @@ meta_output_kms_new (MetaGpuKms        *gpu_kms,
       output_info->height_mm = connector_state->height_mm;
     }
 
+  drm_connector_type = meta_kms_connector_get_connector_type (kms_connector);
+  output_info->connector_type =
+    meta_kms_connector_type_from_drm (drm_connector_type);
+
   if (!init_output_modes (output_info, gpu_kms, kms_connector, error))
     return NULL;
 
@@ -349,10 +385,6 @@ meta_output_kms_new (MetaGpuKms        *gpu_kms,
 
   meta_output_info_parse_edid (output_info, connector_state->edid_data);
 
-  drm_connector_type = meta_kms_connector_get_connector_type (kms_connector);
-  output_info->connector_type =
-    meta_kms_connector_type_from_drm (drm_connector_type);
-
   output_info->tile_info = connector_state->tile_info;
 
   output = g_object_new (META_TYPE_OUTPUT_KMS,
-- 
2.37.1