From f63ebf07f788e232cdb883d8f3b8e9a69c0665d1 Mon Sep 17 00:00:00 2001
From: Wayne Lin <Wayne.Lin@amd.com>
Date: Mon, 28 Jun 2021 15:02:31 +0800
Subject: drm/amd/display: Create dc_sink when EDID fail
Git-commit: 58de0ef2149f762f90bd97cf0bcb425b158488ab
Patch-mainline: v5.15-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

[Why]
While reading remote EDID via Startech 1-to-4 hub, occasionally we
won't get response in time and won't light up corresponding monitor.

Ideally, we can still add generic modes for userspace to choose to try
to light up the monitor and which is done in
drm_helper_probe_single_connector_modes(). So the main problem here is
that we fail .mode_valid since we don't create remote dc_sink for this
case.

[How]
Also add default dc_sink if we can't get the EDID.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 .../display/amdgpu_dm/amdgpu_dm_mst_types.c   | 23 +++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
index 5568d4e518e6..1bcba6943fd7 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
@@ -213,6 +213,29 @@ static int dm_dp_mst_get_modes(struct drm_connector *connector)
 			drm_connector_update_edid_property(
 				&aconnector->base,
 				NULL);
+
+			DRM_DEBUG_KMS("Can't get EDID of %s. Add default remote sink.", connector->name);
+			if (!aconnector->dc_sink) {
+				struct dc_sink *dc_sink;
+				struct dc_sink_init_data init_params = {
+					.link = aconnector->dc_link,
+					.sink_signal = SIGNAL_TYPE_DISPLAY_PORT_MST };
+
+				dc_sink = dc_link_add_remote_sink(
+					aconnector->dc_link,
+					NULL,
+					0,
+					&init_params);
+
+				if (!dc_sink) {
+					DRM_ERROR("Unable to add a remote sink\n");
+					return 0;
+				}
+
+				dc_sink->priv = aconnector;
+				aconnector->dc_sink = dc_sink;
+			}
+
 			return ret;
 		}
 
-- 
2.38.1