drm/amd/display: add new dc debug structure to track debug data

[why]
Some DTN tests still failing @ 2%  Need to reduce.

[how]
add instrumentation code to driver so we can get more information from failed runs.
Signed-off-by: Jun Lei <Jun.Lei@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -1028,6 +1028,9 @@ enum link_training_result dc_link_dp_perform_link_training(
 			lt_settings.lane_settings[0].VOLTAGE_SWING,
 			lt_settings.lane_settings[0].PRE_EMPHASIS);
 
+	if (status != LINK_TRAINING_SUCCESS)
+		link->ctx->dc->debug.debug_data.ltFailCount++;
+
 	return status;
 }
 

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

@@ -259,6 +259,11 @@ struct dc_debug {
 	bool scl_reset_length10;
 	bool hdmi20_disable;
 
+	struct {
+		uint32_t ltFailCount;
+		uint32_t i2cErrorCount;
+		uint32_t auxErrorCount;
+	} debug_data;
 };
 struct dc_state;
 struct resource_pool;