drm/amd/display: Set fec register init value

[Why]
We don't include this eDP FEC init on fastboot.

[How]
Set the fec to init value when stopping driver &get the fec register value to check should enable FEC.
Co-authored-by: Jingwen Zhu <Jingwen.Zhu@amd.com>
Reviewed-by: Wenjing Liu <Wenjing.Liu@amd.com>
Acked-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Jingwen Zhu <Jingwen.Zhu@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/core/dc_link.c

@@ -4683,22 +4683,20 @@ bool dc_link_is_fec_supported(const struct dc_link *link)
 
 bool dc_link_should_enable_fec(const struct dc_link *link)
 {
-	bool is_fec_disable = false;
-	bool ret = false;
+	bool force_disable = false;
 
-	if ((link->connector_signal != SIGNAL_TYPE_DISPLAY_PORT_MST &&
+	if (link->fec_state == dc_link_fec_enabled)
+		force_disable = false;
+	else if (link->connector_signal != SIGNAL_TYPE_DISPLAY_PORT_MST &&
 			link->local_sink &&
-			link->local_sink->edid_caps.panel_patch.disable_fec) ||
-			(link->connector_signal == SIGNAL_TYPE_EDP
-				// enable FEC for EDP if DSC is supported
-				&& link->dpcd_caps.dsc_caps.dsc_basic_caps.fields.dsc_support.DSC_SUPPORT == false
-				))
-		is_fec_disable = true;
-
-	if (dc_link_is_fec_supported(link) && !link->dc->debug.disable_fec && !is_fec_disable)
-		ret = true;
-
-	return ret;
+			link->local_sink->edid_caps.panel_patch.disable_fec)
+		force_disable = true;
+	else if (link->connector_signal == SIGNAL_TYPE_EDP
+			&& link->dpcd_caps.dsc_caps.dsc_basic_caps.fields.
+			 dsc_support.DSC_SUPPORT == false)
+		force_disable = true;
+
+	return !force_disable && dc_link_is_fec_supported(link);
 }
 
 uint32_t dc_bandwidth_in_kbps_from_timing(

drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c

@@ -1493,8 +1493,12 @@ void dcn10_init_hw(struct dc *dc)
 
 		/* Check for enabled DIG to identify enabled display */
 		if (link->link_enc->funcs->is_dig_enabled &&
-			link->link_enc->funcs->is_dig_enabled(link->link_enc))
+			link->link_enc->funcs->is_dig_enabled(link->link_enc)) {
 			link->link_status.link_active = true;
+			if (link->link_enc->funcs->fec_is_active &&
+					link->link_enc->funcs->fec_is_active(link->link_enc))
+				link->fec_state = dc_link_fec_enabled;
+		}
 	}
 
 	/* Power gate DSCs */

drivers/gpu/drm/amd/display/dc/dcn31/dcn31_hwseq.c

@@ -188,8 +188,12 @@ void dcn31_init_hw(struct dc *dc)
 
 		/* Check for enabled DIG to identify enabled display */
 		if (link->link_enc->funcs->is_dig_enabled &&
-			link->link_enc->funcs->is_dig_enabled(link->link_enc))
+			link->link_enc->funcs->is_dig_enabled(link->link_enc)) {
 			link->link_status.link_active = true;
+			if (link->link_enc->funcs->fec_is_active &&
+					link->link_enc->funcs->fec_is_active(link->link_enc))
+				link->fec_state = dc_link_fec_enabled;
+		}
 	}
 
 	/* Enables outbox notifications for usb4 dpia */