From: Ken Chalmers <ken.chalmers@amd.com>
Date: Thu, 4 May 2017 13:34:55 -0400
Subject: drm/amd/display: Continue with stream enable if DP link training
 fails.
Git-commit: c0ba5ec70eff5cf0e4337b3864c94fa6b128c8d7
Patch-mainline: v4.15-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

Not necessarily a fatal problem - some monitors will recover and show
the stream anyway if link training fails.

Signed-off-by: Ken Chalmers <ken.chalmers@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_link.c    |   21 +++++++++++++++++----
 drivers/gpu/drm/amd/display/dc/inc/core_status.h |    1 +
 2 files changed, 18 insertions(+), 4 deletions(-)

--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -1225,7 +1225,7 @@ static enum dc_status enable_link_dp(str
 		status = DC_OK;
 	}
 	else
-		status = DC_ERROR_UNEXPECTED;
+		status = DC_FAIL_DP_LINK_TRAINING;
 
 	enable_stream_features(pipe_ctx);
 
@@ -1833,9 +1833,22 @@ void core_link_enable_stream(struct pipe
 {
 	struct core_dc *core_dc = DC_TO_CORE(pipe_ctx->stream->ctx->dc);
 
-	if (DC_OK != enable_link(pipe_ctx)) {
-			BREAK_TO_DEBUGGER();
-			return;
+	enum dc_status status = enable_link(pipe_ctx);
+
+	if (status != DC_OK) {
+			dm_logger_write(pipe_ctx->stream->ctx->logger,
+			LOG_WARNING, "enabling link %u failed: %d\n",
+			pipe_ctx->stream->sink->link->public.link_index,
+			status);
+
+			/* Abort stream enable *unless* the failure was due to
+			 * DP link training - some DP monitors will recover and
+			 * show the stream anyway.
+			 */
+			if (status != DC_FAIL_DP_LINK_TRAINING) {
+				BREAK_TO_DEBUGGER();
+				return;
+			}
 	}
 
 	/* turn off otg test pattern if enable */
--- a/drivers/gpu/drm/amd/display/dc/inc/core_status.h
+++ b/drivers/gpu/drm/amd/display/dc/inc/core_status.h
@@ -41,6 +41,7 @@ enum dc_status {
 	DC_SURFACE_PIXEL_FORMAT_UNSUPPORTED = 11,
 	DC_FAIL_BANDWIDTH_VALIDATE = 12, /* BW and Watermark validation */
 	DC_FAIL_SCALING = 13,
+	DC_FAIL_DP_LINK_TRAINING = 14,
 
 	DC_ERROR_UNEXPECTED = -1
 };