[PATCH 09/14] drm/amd/display: Fixed Clock Recovery Sequence

[Solomon Chiu]

From: David Galiffi <David.Galiffi at amd.com>

[Why]
When performing clock recovery, if a pre-emphasis adjustment is
requested, but voltage swing remains constant, the the retry counter
will not be reset. This can lead to prematurely failing link training.

[How]
Reset the clock recovery retry counter if an adjustment is requested
for either voltage swing or pre-emphasis.

Signed-off-by: Calvin Hou <Calvin.Hou at amd.com>
Signed-off-by: David Galiffi <David.Galiffi at amd.com>
Reviewed-by: Jun Lei <Jun.Lei at amd.com>
Acked-by: Solomon Chiu <solomon.chiu at amd.com>
---
 drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 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 47e6c33f73cb..484d96f78ade 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
@@ -1098,11 +1098,13 @@ static enum link_training_result perform_clock_recovery_sequence(
 		if (is_max_vs_reached(lt_settings))
 			break;
 
-		/* 7. same voltage*/
-		/* Note: VS same for all lanes,
-		* so comparing first lane is sufficient*/
-		if (lt_settings->lane_settings[0].VOLTAGE_SWING ==
+		/* 7. same lane settings*/
+		/* Note: settings are the same for all lanes,
+		 * so comparing first lane is sufficient*/
+		if ((lt_settings->lane_settings[0].VOLTAGE_SWING ==
 			req_settings.lane_settings[0].VOLTAGE_SWING)
+			&& (lt_settings->lane_settings[0].PRE_EMPHASIS ==
+				req_settings.lane_settings[0].PRE_EMPHASIS))
 			retries_cr++;
 		else
 			retries_cr = 0;
-- 
2.29.0