drm/amd/display: Retain phantom pipes when min transition into subvp (#7358)

[Description]
- When entering into a SubVP config that requires a minimal
transition we need to retain phantom pipes and also restore
the mall config
- This is because the min transition will remove phantom pipes
from the context (shallow copy) and not restore it's original
state
- This is just a workaround, and needs a proper fix

Reviewed-by: Jun Lei <[e-mail]>
Acked-by: Jasdeep Dhillon <[e-mail]>
Signed-off-by: Alvin Lee <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/display/dc/core/dc.c

···
 	struct dc_state *context;
 	enum surface_update_type update_type;
 	int i;
+	struct mall_temp_config mall_temp_config;
 
 	/* In cases where MPO and split or ODM are used transitions can
 	 * cause underflow. Apply stream configuration with minimal pipe
···
 
 	/* on plane removal, minimal state is the new one */
 	if (force_minimal_pipe_splitting && !is_plane_addition) {
+		/* Since all phantom pipes are removed in full validation,
+		 * we have to save and restore the subvp/mall config when
+		 * we do a minimal transition since the flags marking the
+		 * pipe as subvp/phantom will be cleared (dc copy constructor
+		 * creates a shallow copy).
+		 */
+		if (dc->res_pool->funcs->save_mall_state)
+			dc->res_pool->funcs->save_mall_state(dc, context, &mall_temp_config);
 		if (!commit_minimal_transition_state(dc, context)) {
 			dc_release_state(context);
 			return false;
 		}
+		if (dc->res_pool->funcs->restore_mall_state)
+			dc->res_pool->funcs->restore_mall_state(dc, context, &mall_temp_config);
 
+		/* If we do a minimal transition with plane removal and the context
+		 * has subvp we also have to retain back the phantom stream / planes
+		 * since the refcount is decremented as part of the min transition
+		 * (we commit a state with no subvp, so the phantom streams / planes
+		 * had to be removed).
+		 */
+		if (dc->res_pool->funcs->retain_phantom_pipes)
+			dc->res_pool->funcs->retain_phantom_pipes(dc, context);
 		update_type = UPDATE_TYPE_FULL;
 	}
 

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

···
 	struct dc_stream_state *paired_stream;	// master / slave stream
 };
 
+/* Temp struct used to save and restore MALL config
+ * during validation.
+ *
+ * TODO: Move MALL config into dc_state instead of stream struct
+ * to avoid needing to save/restore.
+ */
+struct mall_temp_config {
+	struct mall_stream_config mall_stream_config[MAX_PIPES];
+	bool is_phantom_plane[MAX_PIPES];
+};
+
 struct dc_stream_state {
 	// sink is deprecated, new code should not reference
 	// this pointer

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

···
 	.add_phantom_pipes = dcn32_add_phantom_pipes,
 	.remove_phantom_pipes = dcn32_remove_phantom_pipes,
 	.retain_phantom_pipes = dcn32_retain_phantom_pipes,
+	.save_mall_state = dcn32_save_mall_state,
+	.restore_mall_state = dcn32_restore_mall_state,
 };
 
 

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

···
 extern struct _vcs_dpi_ip_params_st dcn3_2_ip;
 extern struct _vcs_dpi_soc_bounding_box_st dcn3_2_soc;
 
-/* Temp struct used to save and restore MALL config
- * during validation.
- *
- * TODO: Move MALL config into dc_state instead of stream struct
- * to avoid needing to save/restore.
- */
-struct mall_temp_config {
-	struct mall_stream_config mall_stream_config[MAX_PIPES];
-	bool is_phantom_plane[MAX_PIPES];
-};
-
 struct dcn32_resource_pool {
 	struct resource_pool base;
 };

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

···
 	.add_phantom_pipes = dcn32_add_phantom_pipes,
 	.remove_phantom_pipes = dcn32_remove_phantom_pipes,
 	.retain_phantom_pipes = dcn32_retain_phantom_pipes,
+	.save_mall_state = dcn32_save_mall_state,
+	.restore_mall_state = dcn32_restore_mall_state,
 };
 
 

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

···
 	bool (*remove_phantom_pipes)(struct dc *dc, struct dc_state *context, bool fast_update);
 	void (*retain_phantom_pipes)(struct dc *dc, struct dc_state *context);
 	void (*get_panel_config_defaults)(struct dc_panel_config *panel_config);
+	void (*save_mall_state)(struct dc *dc, struct dc_state *context, struct mall_temp_config *temp_config);
+	void (*restore_mall_state)(struct dc *dc, struct dc_state *context, struct mall_temp_config *temp_config);
 };
 
 struct audio_support{