Commit 3d223c55 authored by David Galiffi's avatar David Galiffi Committed by Alex Deucher
Browse files

drm/amd/display: Fixed Clock Recovery Sequence 



[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.

Tested-by: default avatarDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: default avatarCalvin Hou <Calvin.Hou@amd.com>
Signed-off-by: default avatarDavid Galiffi <David.Galiffi@amd.com>
Reviewed-by: default avatarJun Lei <Jun.Lei@amd.com>
Acked-by: default avatarSolomon Chiu <solomon.chiu@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent 4aa8607e

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

+6 −4
Original line number Diff line number Diff line
@@ -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,

		/* 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 ==

		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;