drm/amd/display: Retain phantom plane/stream if validation fails

[Description]
- If we fail validation, we should retain the phantom
  stream/planes
- Full updates assume that phantom pipes will be fully
  removed, but if validation fails we keep the phantom
  pipes
- Therefore we have to retain the plane/stream if validation
  fails (since the refcount is decremented before validation,
  and the expectation is that it's fully freed when the  old
  dc_state is released)
Reviewed-by: NJun Lei <Jun.Lei@amd.com>
Acked-by: NBrian Chang <Brian.Chang@amd.com>
Signed-off-by: NAlvin Lee <Alvin.Lee2@amd.com>
Tested-by: NDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

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

@@ -3098,6 +3098,19 @@ static bool update_planes_and_stream_state(struct dc *dc,
 
 	if (update_type == UPDATE_TYPE_FULL) {
 		if (!dc->res_pool->funcs->validate_bandwidth(dc, context, false)) {
+			/* For phantom pipes we remove and create a new set of phantom pipes
+			 * for each full update (because we don't know if we'll need phantom
+			 * pipes until after the first round of validation). However, if validation
+			 * fails we need to keep the existing phantom pipes (because we don't update
+			 * the dc->current_state).
+			 *
+			 * The phantom stream/plane refcount is decremented for validation because
+			 * we assume it'll be removed (the free comes when the dc_state is freed),
+			 * but if validation fails we have to increment back the refcount so it's
+			 * consistent.
+			 */
+			if (dc->res_pool->funcs->retain_phantom_pipes)
+				dc->res_pool->funcs->retain_phantom_pipes(dc, dc->current_state);
 			BREAK_TO_DEBUGGER();
 			goto fail;
 		}

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

@@ -1721,6 +1721,27 @@ static struct dc_stream_state *dcn32_enable_phantom_stream(struct dc *dc,
 	return phantom_stream;
 }
 
+void dcn32_retain_phantom_pipes(struct dc *dc, struct dc_state *context)
+{
+	int i;
+	struct dc_plane_state *phantom_plane = NULL;
+	struct dc_stream_state *phantom_stream = NULL;
+
+	for (i = 0; i < dc->res_pool->pipe_count; i++) {
+		struct pipe_ctx *pipe = &context->res_ctx.pipe_ctx[i];
+
+		if (!pipe->top_pipe && !pipe->prev_odm_pipe &&
+				pipe->plane_state && pipe->stream &&
+				pipe->stream->mall_stream_config.type == SUBVP_PHANTOM) {
+			phantom_plane = pipe->plane_state;
+			phantom_stream = pipe->stream;
+
+			dc_plane_state_retain(phantom_plane);
+			dc_stream_retain(phantom_stream);
+		}
+	}
+}
+
 // return true if removed piped from ctx, false otherwise
 bool dcn32_remove_phantom_pipes(struct dc *dc, struct dc_state *context)
 {
@@ -2033,6 +2054,7 @@ static struct resource_funcs dcn32_res_pool_funcs = {
 	.update_soc_for_wm_a = dcn30_update_soc_for_wm_a,
 	.add_phantom_pipes = dcn32_add_phantom_pipes,
 	.remove_phantom_pipes = dcn32_remove_phantom_pipes,
+	.retain_phantom_pipes = dcn32_retain_phantom_pipes,
 };
 
 

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

@@ -83,6 +83,9 @@ bool dcn32_release_post_bldn_3dlut(
 bool dcn32_remove_phantom_pipes(struct dc *dc,
 		struct dc_state *context);
 
+void dcn32_retain_phantom_pipes(struct dc *dc,
+		struct dc_state *context);
+
 void dcn32_add_phantom_pipes(struct dc *dc,
 		struct dc_state *context,
 		display_e2e_pipe_params_st *pipes,

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

@@ -1621,6 +1621,7 @@ static struct resource_funcs dcn321_res_pool_funcs = {
 	.update_soc_for_wm_a = dcn30_update_soc_for_wm_a,
 	.add_phantom_pipes = dcn32_add_phantom_pipes,
 	.remove_phantom_pipes = dcn32_remove_phantom_pipes,
+	.retain_phantom_pipes = dcn32_retain_phantom_pipes,
 };
 
 

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

@@ -241,6 +241,7 @@ struct resource_funcs {
             unsigned int index);
 
 	bool (*remove_phantom_pipes)(struct dc *dc, struct dc_state *context);
+	void (*retain_phantom_pipes)(struct dc *dc, struct dc_state *context);
 	void (*get_panel_config_defaults)(struct dc_panel_config *panel_config);
 };