drm/amd/display: retain/release at proper places in link_enc assignment

[why]
Need to keep track of number of
references to stream pointer.

[how]
Call stream retain/release whenever
necessary in link_enc table assignment
sequence.
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Sung Joon Kim <sungkim@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.c

@@ -808,6 +808,10 @@ void dc_stream_set_static_screen_params(struct dc *dc,
 
 static void dc_destruct(struct dc *dc)
 {
+	// reset link encoder assignment table on destruct
+	if (dc->res_pool->funcs->link_encs_assign)
+		link_enc_cfg_init(dc, dc->current_state);
+
 	if (dc->current_state) {
 		dc_release_state(dc->current_state);
 		dc->current_state = NULL;

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

@@ -151,6 +151,7 @@ static void add_link_enc_assignment(
 						.ep_type = stream->link->ep_type},
 					.eng_id = eng_id,
 					.stream = stream};
+				dc_stream_retain(stream);
 				state->res_ctx.link_enc_cfg_ctx.link_enc_avail[eng_idx] = ENGINE_ID_UNKNOWN;
 				stream->link_enc = stream->ctx->dc->res_pool->link_encoders[eng_idx];
 				break;
@@ -247,7 +248,10 @@ static void clear_enc_assignments(const struct dc *dc, struct dc_state *state)
 	for (i = 0; i < MAX_PIPES; i++) {
 		state->res_ctx.link_enc_cfg_ctx.link_enc_assignments[i].valid = false;
 		state->res_ctx.link_enc_cfg_ctx.link_enc_assignments[i].eng_id = ENGINE_ID_UNKNOWN;
-		state->res_ctx.link_enc_cfg_ctx.link_enc_assignments[i].stream = NULL;
+		if (state->res_ctx.link_enc_cfg_ctx.link_enc_assignments[i].stream != NULL) {
+			dc_stream_release(state->res_ctx.link_enc_cfg_ctx.link_enc_assignments[i].stream);
+			state->res_ctx.link_enc_cfg_ctx.link_enc_assignments[i].stream = NULL;
+		}
 	}
 
 	for (i = 0; i < dc->res_pool->res_cap->num_dig_link_enc; i++) {