From: Eric Yang <Eric.Yang2@amd.com>
Date: Thu, 8 Feb 2018 14:05:14 -0500
Subject: drm/amd/display: Treat bad EDID as no EDID
Git-commit: 6531738842dbc84ced7514b8934d7d43fae74680
Patch-mainline: v4.17-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

We have an mst dock firmware that will emulate an EDID with bad
checksum.

v2: Tread -> Treat

Signed-off-by: Eric Yang <Eric.Yang2@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/amd/display/dc/core/dc.c |   13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

--- a/drivers/gpu/drm/amd/display/dc/core/dc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
@@ -1637,12 +1637,17 @@ struct dc_sink *dc_link_add_remote_sink(
 			&dc_sink->dc_edid,
 			&dc_sink->edid_caps);
 
-	if (edid_status != EDID_OK)
-		goto fail;
+	/*
+	 * Treat device as no EDID device if EDID
+	 * parsing fails
+	 */
+	if (edid_status != EDID_OK) {
+		dc_sink->dc_edid.length = 0;
+		dm_error("Bad EDID, status%d!\n", edid_status);
+	}
 
 	return dc_sink;
-fail:
-	dc_link_remove_remote_sink(link, dc_sink);
+
 fail_add_sink:
 	dc_sink_release(dc_sink);
 	return NULL;