drm/amd/display: keep eDP Vdd on when eDP stream is already enabled

[Why]
Even if can_apply_edp_fast_boot is set to 1 at boot, this flag will
be cleared to 0 at S3 resume.

[How]
Keep eDP Vdd on when eDP stream is already enabled.
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Jasdeep Dhillon <jdhillon@amd.com>
Signed-off-by: Zhan Liu <Zhan.Liu@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/dce110/dce110_hw_sequencer.c

@@ -1834,9 +1834,29 @@ void dce110_enable_accelerated_mode(struct dc *dc, struct dc_state *context)
 				break;
 			}
 		}
-		// We are trying to enable eDP, don't power down VDD
-		if (can_apply_edp_fast_boot)
+
+		/*
+		 * TO-DO: So far the code logic below only addresses single eDP case.
+		 * For dual eDP case, there are a few things that need to be
+		 * implemented first:
+		 *
+		 * 1. Change the fastboot logic above, so eDP link[0 or 1]'s
+		 * stream[0 or 1] will all be checked.
+		 *
+		 * 2. Change keep_edp_vdd_on to an array, and maintain keep_edp_vdd_on
+		 * for each eDP.
+		 *
+		 * Once above 2 things are completed, we can then change the logic below
+		 * correspondingly, so dual eDP case will be fully covered.
+		 */
+
+		// We are trying to enable eDP, don't power down VDD if eDP stream is existing
+		if ((edp_stream_num == 1 && edp_streams[0] != NULL) || can_apply_edp_fast_boot) {
 			keep_edp_vdd_on = true;
+			DC_LOG_EVENT_LINK_TRAINING("Keep eDP Vdd on\n");
+		} else {
+			DC_LOG_EVENT_LINK_TRAINING("No eDP stream enabled, turn eDP Vdd off\n");
+		}
 	}
 
 	// Check seamless boot support