drm/amd/display: move MST branch initialize to before link training

some MST capable scaler doesn't like recieving CLEAR_PAYLOAD_ID_TABLE after
link training.  move branch initialize to before link training
Signed-off-by: Hersen Wu <hersenxs.wu@amd.com>
Signed-off-by: Tony Cheng <tony.cheng@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/amdgpu_dm/amdgpu_dm_helpers.c

@@ -258,6 +258,15 @@ bool dm_helpers_dp_mst_write_payload_allocation_table(
 	return true;
 }
 
+
+/*
+ * Clear payload allocation table before enable MST DP link.
+ */
+void dm_helpers_dp_mst_clear_payload_allocation_table(
+	struct dc_context *ctx,
+	const struct dc_link *link)
+{}
+
 /*
  * Polls for ACT (allocation change trigger) handled and sends
  * ALLOCATE_PAYLOAD message.

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

@@ -1311,6 +1311,9 @@ static enum dc_status enable_link_dp_mst(
 	if (link->cur_link_settings.lane_count != LANE_COUNT_UNKNOWN)
 		return DC_OK;
 
+	/* clear payload table */
+	dm_helpers_dp_mst_clear_payload_allocation_table(link->ctx, link);
+
 	/* set the sink to MST mode before enabling the link */
 	dp_enable_mst_on_sink(link, true);
 

drivers/gpu/drm/amd/display/dc/dm_helpers.h

@@ -49,6 +49,13 @@ bool dm_helpers_dp_mst_write_payload_allocation_table(
 		struct dp_mst_stream_allocation_table *proposed_table,
 		bool enable);
 
+/*
+ * Clear payload allocation table before enable MST DP link.
+ */
+void dm_helpers_dp_mst_clear_payload_allocation_table(
+	struct dc_context *ctx,
+	const struct dc_link *link);
+
 /*
  * Polls for ACT (allocation change trigger) handled and
  */