drm/amd/display: add interface to query SubVP status

[Why&How]
To enable automated testing through IGT, expose an API that is
accessible through debugfs to query current status of SubVP feature.
Reviewed-by: Alvin Lee <alvin.lee2@amd.com>
Acked-by: Roman Li <roman.li@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -3645,7 +3645,9 @@ static int capabilities_show(struct seq_file *m, void *unused)
 	struct amdgpu_device *adev = (struct amdgpu_device *)m->private;
 	struct dc *dc = adev->dm.dc;
 	bool mall_supported = dc->caps.mall_size_total;
+	bool subvp_supported = dc->caps.subvp_fw_processing_delay_us;
 	unsigned int mall_in_use = false;
+	unsigned int subvp_in_use = dc->cap_funcs.get_subvp_en(dc, dc->current_state);
 	struct hubbub *hubbub = dc->res_pool->hubbub;
 
 	if (hubbub->funcs->get_mall_en)
@@ -3653,6 +3655,8 @@ static int capabilities_show(struct seq_file *m, void *unused)
 
 	seq_printf(m, "mall supported: %s, enabled: %s\n",
 			   mall_supported ? "yes" : "no", mall_in_use ? "yes" : "no");
+	seq_printf(m, "sub-viewport supported: %s, enabled: %s\n",
+			   subvp_supported ? "yes" : "no", subvp_in_use ? "yes" : "no");
 
 	return 0;
 }

drivers/gpu/drm/amd/display/dc/dc.h

@@ -382,6 +382,7 @@ struct dc_cap_funcs {
 	bool (*get_dcc_compression_cap)(const struct dc *dc,
 			const struct dc_dcc_surface_param *input,
 			struct dc_surface_dcc_cap *output);
+	bool (*get_subvp_en)(struct dc *dc, struct dc_state *context);
 };
 
 struct link_training_settings;

drivers/gpu/drm/amd/display/dc/dcn32/dcn32_resource.c

@@ -1993,7 +1993,8 @@ int dcn32_populate_dml_pipes_from_context(
 }
 
 static struct dc_cap_funcs cap_funcs = {
-	.get_dcc_compression_cap = dcn20_get_dcc_compression_cap
+	.get_dcc_compression_cap = dcn20_get_dcc_compression_cap,
+	.get_subvp_en = dcn32_subvp_in_use,
 };
 
 void dcn32_calculate_wm_and_dlg(struct dc *dc, struct dc_state *context,

drivers/gpu/drm/amd/display/dc/dcn321/dcn321_resource.c

@@ -1571,7 +1571,8 @@ static void dcn321_destroy_resource_pool(struct resource_pool **pool)
 }
 
 static struct dc_cap_funcs cap_funcs = {
-	.get_dcc_compression_cap = dcn20_get_dcc_compression_cap
+	.get_dcc_compression_cap = dcn20_get_dcc_compression_cap,
+	.get_subvp_en = dcn32_subvp_in_use,
 };
 
 static void dcn321_update_bw_bounding_box(struct dc *dc, struct clk_bw_params *bw_params)