drm/amd/display: Continue with stream enable if DP link training fails.

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>

drivers/gpu/drm/amd/display/dc/core/dc_link.c

@@ -1225,7 +1225,7 @@ static enum dc_status enable_link_dp(struct pipe_ctx *pipe_ctx)
 		status = DC_OK;
 	}
 	else
-		status = DC_ERROR_UNEXPECTED;
+		status = DC_FAIL_DP_LINK_TRAINING;
 
 	enable_stream_features(pipe_ctx);
 
@@ -1833,10 +1833,23 @@ void core_link_enable_stream(struct pipe_ctx *pipe_ctx)
 {
 	struct core_dc *core_dc = DC_TO_CORE(pipe_ctx->stream->ctx->dc);
 
-	if (DC_OK != enable_link(pipe_ctx)) {
+	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 */
 	pipe_ctx->tg->funcs->set_test_pattern(pipe_ctx->tg,

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
 };