drm/amd/display: Fix fallback issues for DP LL 1.4a tests

[WHY]
Unlike DP or USBC, the USB4 link does not get its own encoder and
has to share therefore verify_caps is skipped.

[HOW]
Fix the fallback logic for automated tests and take that
into consideration for LT and LS.
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Alan Liu <HaoPing.Liu@amd.com>
Signed-off-by: Mustapha Ghaddar <mustapha.ghaddar@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -4554,10 +4554,20 @@ void dc_link_dp_handle_link_loss(struct dc_link *link)
 
 	for (i = 0; i < MAX_PIPES; i++) {
 		pipe_ctx = &link->dc->current_state->res_ctx.pipe_ctx[i];
-		if (pipe_ctx && pipe_ctx->stream && !pipe_ctx->stream->dpms_off &&
-				pipe_ctx->stream->link == link && !pipe_ctx->prev_odm_pipe)
+		if (pipe_ctx && pipe_ctx->stream && !pipe_ctx->stream->dpms_off
+				&& pipe_ctx->stream->link == link && !pipe_ctx->prev_odm_pipe) {
+			// Always use max settings here for DP 1.4a LL Compliance CTS
+			if (link->is_automated) {
+				pipe_ctx->link_config.dp_link_settings.lane_count =
+						link->verified_link_cap.lane_count;
+				pipe_ctx->link_config.dp_link_settings.link_rate =
+						link->verified_link_cap.link_rate;
+				pipe_ctx->link_config.dp_link_settings.link_spread =
+						link->verified_link_cap.link_spread;
+			}
 			core_link_enable_stream(link->dc->current_state, pipe_ctx);
 		}
+	}
 }
 
 bool dc_link_handle_hpd_rx_irq(struct dc_link *link, union hpd_irq_data *out_hpd_irq_dpcd_data, bool *out_link_loss,
@@ -4597,6 +4607,8 @@ bool dc_link_handle_hpd_rx_irq(struct dc_link *link, union hpd_irq_data *out_hpd
 	}
 
 	if (hpd_irq_dpcd_data.bytes.device_service_irq.bits.AUTOMATED_TEST) {
+		// Workaround for DP 1.4a LL Compliance CTS as USB4 has to share encoders unlike DP and USBC
+		link->is_automated = true;
 		device_service_clear.bits.AUTOMATED_TEST = 1;
 		core_link_write_dpcd(
 			link,
@@ -7240,6 +7252,7 @@ void dp_retrain_link_dp_test(struct dc_link *link,
 	struct pipe_ctx *pipes =
 			&link->dc->current_state->res_ctx.pipe_ctx[0];
 	unsigned int i;
+	bool do_fallback = false;
 
 
 	for (i = 0; i < MAX_PIPES; i++) {
@@ -7272,13 +7285,16 @@ void dp_retrain_link_dp_test(struct dc_link *link,
 			memset(&link->cur_link_settings, 0,
 				sizeof(link->cur_link_settings));
 
+			if (link->ep_type == DISPLAY_ENDPOINT_USB4_DPIA)
+				do_fallback = true;
+
 			perform_link_training_with_retries(
 					link_setting,
 					skip_video_pattern,
 					LINK_TRAINING_ATTEMPTS,
 					&pipes[i],
 					SIGNAL_TYPE_DISPLAY_PORT,
-					false);
+					do_fallback);
 
 			link->dc->hwss.enable_stream(&pipes[i]);
 

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

@@ -791,11 +791,15 @@ static enum link_training_result dpia_training_eq_transparent(
 		}
 
 		if (dp_is_ch_eq_done(lane_count, dpcd_lane_status) &&
-		    dp_is_symbol_locked(link->cur_link_settings.lane_count, dpcd_lane_status) &&
-		    dp_is_interlane_aligned(dpcd_lane_status_updated)) {
+				dp_is_symbol_locked(link->cur_link_settings.lane_count, dpcd_lane_status)) {
+			/* Take into consideration corner case for DP 1.4a LL Compliance CTS as USB4
+			 * has to share encoders unlike DP and USBC
+			 */
+			if (dp_is_interlane_aligned(dpcd_lane_status_updated) || (link->is_automated && retries_eq)) {
 				result =  LINK_TRAINING_SUCCESS;
 				break;
 			}
+		}
 
 		/* Update VS/PE. */
 		dp_decide_lane_settings(lt_settings, dpcd_lane_adjust,
@@ -1008,6 +1012,7 @@ enum link_training_result dc_link_dpia_perform_link_training(
 	 */
 	if (result == LINK_TRAINING_SUCCESS) {
 		msleep(5);
+		if (!link->is_automated)
 			result = dp_check_link_loss_status(link, &lt_settings);
 	} else if (result == LINK_TRAINING_ABORT) {
 		dpia_training_abort(link, &lt_settings, repeater_id);

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

@@ -184,6 +184,7 @@ struct dc_link {
 	bool is_dig_mapping_flexible;
 	bool hpd_status; /* HPD status of link without physical HPD pin. */
 	bool is_hpd_pending; /* Indicates a new received hpd */
+	bool is_automated; /* Indicates automated testing */
 
 	bool edp_sink_present;