drm/amd/display: Create one virtual connector in DC

[WHAT]
Prepare a virtual connector for writeback.
Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -1693,6 +1693,10 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
 	init_data.nbio_reg_offsets = adev->reg_offset[NBIO_HWIP][0];
 	init_data.clk_reg_offsets = adev->reg_offset[CLK_HWIP][0];
 
+	/* Enable DWB for tested platforms only */
+	if (adev->ip_versions[DCE_HWIP][0] >= IP_VERSION(3, 0, 0))
+		init_data.num_virtual_links = 1;
+
 	INIT_LIST_HEAD(&adev->dm.da_list);
 
 	retrieve_dmi_info(&adev->dm);
@@ -4506,6 +4510,11 @@ static int amdgpu_dm_initialize_drm_device(struct amdgpu_device *adev)
 			continue;
 		}
 
+		link = dc_get_link_at_index(dm->dc, i);
+
+		if (link->connector_signal == SIGNAL_TYPE_VIRTUAL)
+			continue;
+
 		aconnector = kzalloc(sizeof(*aconnector), GFP_KERNEL);
 		if (!aconnector)
 			goto fail;
@@ -4524,8 +4533,6 @@ static int amdgpu_dm_initialize_drm_device(struct amdgpu_device *adev)
 			goto fail;
 		}
 
-		link = dc_get_link_at_index(dm->dc, i);
-
 		if (!dc_link_detect_connection_type(link, &new_connection_type))
 			DRM_ERROR("KMS: Failed to detect connector\n");
 

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

@@ -96,7 +96,8 @@ static void enable_memory_low_power(struct dc *dc)
 	if (dc->debug.enable_mem_low_power.bits.vpg && dc->res_pool->stream_enc[0]->vpg->funcs->vpg_powerdown) {
 		// Power down VPGs
 		for (i = 0; i < dc->res_pool->stream_enc_count; i++)
-			dc->res_pool->stream_enc[i]->vpg->funcs->vpg_powerdown(dc->res_pool->stream_enc[i]->vpg);
+			if (dc->res_pool->stream_enc[i]->vpg)
+				dc->res_pool->stream_enc[i]->vpg->funcs->vpg_powerdown(dc->res_pool->stream_enc[i]->vpg);
 #if defined(CONFIG_DRM_AMD_DC_FP)
 		for (i = 0; i < dc->res_pool->hpo_dp_stream_enc_count; i++)
 			dc->res_pool->hpo_dp_stream_enc[i]->vpg->funcs->vpg_powerdown(dc->res_pool->hpo_dp_stream_enc[i]->vpg);