[PATCH] Revert "drm/amd/display: Check lane status again after link training done"

[Alex Deucher]

This reverts commit 3fd20292c2352660155bbc11736dd014b2fc6e98.

Fixes a display corruption issue on resume and undetected
modes on some monitors.

Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1424
Bug: https://bugzilla.kernel.org/show_bug.cgi?id=208947
Cc: Martin Tsai <martin.tsai at amd.com>
Cc: Aric Cyr <Aric.Cyr at amd.com>
Cc: Eryk Brol <eryk.brol at amd.com>
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
---
 .../gpu/drm/amd/display/dc/core/dc_link_dp.c  | 49 -------------------
 .../amd/display/include/link_service_types.h  |  2 -
 2 files changed, 51 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
index c1391bfb7a9b..4aed57ce69e0 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
@@ -1165,44 +1165,6 @@ static inline enum link_training_result perform_link_training_int(
 	return status;
 }
 
-static enum link_training_result check_link_loss_status(
-	struct dc_link *link,
-	const struct link_training_settings *link_training_setting)
-{
-	enum link_training_result status = LINK_TRAINING_SUCCESS;
-	union lane_status lane_status;
-	uint8_t dpcd_buf[6] = {0};
-	uint32_t lane;
-
-	core_link_read_dpcd(
-			link,
-			DP_SINK_COUNT,
-			(uint8_t *)(dpcd_buf),
-			sizeof(dpcd_buf));
-
-	/*parse lane status*/
-	for (lane = 0; lane < link->cur_link_settings.lane_count; lane++) {
-		/*
-		 * check lanes status
-		 */
-		lane_status.raw = get_nibble_at_index(&dpcd_buf[2], lane);
-
-		if (!lane_status.bits.CHANNEL_EQ_DONE_0 ||
-			!lane_status.bits.CR_DONE_0 ||
-			!lane_status.bits.SYMBOL_LOCKED_0) {
-			/* if one of the channel equalization, clock
-			 * recovery or symbol lock is dropped
-			 * consider it as (link has been
-			 * dropped) dp sink status has changed
-			 */
-			status = LINK_TRAINING_LINK_LOSS;
-			break;
-		}
-	}
-
-	return status;
-}
-
 static void initialize_training_settings(
 	 struct dc_link *link,
 	const struct dc_link_settings *link_setting,
@@ -1455,9 +1417,6 @@ static void print_status_message(
 	case LINK_TRAINING_LQA_FAIL:
 		lt_result = "LQA failed";
 		break;
-	case LINK_TRAINING_LINK_LOSS:
-		lt_result = "Link loss";
-		break;
 	default:
 		break;
 	}
@@ -1616,14 +1575,6 @@ enum link_training_result dc_link_dp_perform_link_training(
 				status);
 	}
 
-	/* delay 5ms after Main Link output idle pattern and then check
-	 * DPCD 0202h.
-	 */
-	if (link->connector_signal != SIGNAL_TYPE_EDP && status == LINK_TRAINING_SUCCESS) {
-		msleep(5);
-		status = check_link_loss_status(link, &lt_settings);
-	}
-
 	/* 6. print status message*/
 	print_status_message(link, &lt_settings, status);
 
diff --git a/drivers/gpu/drm/amd/display/include/link_service_types.h b/drivers/gpu/drm/amd/display/include/link_service_types.h
index 7392a89e771f..50720bbbbaf6 100644
--- a/drivers/gpu/drm/amd/display/include/link_service_types.h
+++ b/drivers/gpu/drm/amd/display/include/link_service_types.h
@@ -66,8 +66,6 @@ enum link_training_result {
 	/* other failure during EQ step */
 	LINK_TRAINING_EQ_FAIL_EQ,
 	LINK_TRAINING_LQA_FAIL,
-	/* one of the CR,EQ or symbol lock is dropped */
-	LINK_TRAINING_LINK_LOSS,
 };
 
 struct link_training_settings {
-- 
2.29.2