drm/amd/display: Apply correct panel mode when reinitializing hardware

[Why]
When link training during engine recovery, ASSR might fail causing panel
mode to be reset to default. This should not happen for eDP as it
will prevent the panel from turning back on.

[How]
Added dp_panel_mode to struct dc_link to remember previously applied
panel mode. Do not reset panel mode to default while performing link
training if previously used panel mode = eDP.
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Michael Mityushkin <michael.mityushkin@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/dc.h

@@ -1456,6 +1456,7 @@ struct dc_link {
 
 	struct ddc_service *ddc;
 
+	enum dp_panel_mode panel_mode;
 	bool aux_mode;
 
 	/* Private to DC core */

drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training.c

@@ -1596,7 +1596,10 @@ bool perform_link_training_with_retries(
 				 * Report and continue with eDP panel mode to
 				 * perform eDP link training with right settings
 				 */
-				cp_psp->funcs.enable_assr(cp_psp->handle, link);
+				bool result;
+				result = cp_psp->funcs.enable_assr(cp_psp->handle, link);
+				if (!result && link->panel_mode != DP_PANEL_MODE_EDP)
+					panel_mode = DP_PANEL_MODE_DEFAULT;
 			}
 		}
 

drivers/gpu/drm/amd/display/dc/link/protocols/link_edp_panel_control.c

@@ -83,6 +83,7 @@ void dp_set_panel_mode(struct dc_link *link, enum dp_panel_mode panel_mode)
 			ASSERT(result == DC_OK);
 		}
 	}
+	link->panel_mode = panel_mode;
 	DC_LOG_DETECTION_DP_CAPS("Link: %d eDP panel mode supported: %d "
 		 "eDP panel mode enabled: %d \n",
 		 link->link_index,