drm/amd/display: Check pipe_ctx before it is used

resource_get_odm_slice_count and resource_get_otg_master_for_stream can
return null, and their returns must be checked before used.

This fixes 4 NULL_RETURNS issues reported by Coverity.
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Acked-by: Hamza Mahfooz <hamza.mahfooz@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/dc/core/dc_resource.c

@@ -3127,9 +3127,14 @@ bool resource_update_pipes_for_stream_with_slice_count(
 	int i;
 	struct pipe_ctx *otg_master = resource_get_otg_master_for_stream(
 			&new_ctx->res_ctx, stream);
-	int cur_slice_count = resource_get_odm_slice_count(otg_master);
+	int cur_slice_count;
 	bool result = true;
 
+	if (!otg_master)
+		return false;
+
+	cur_slice_count = resource_get_odm_slice_count(otg_master);
+
 	if (new_slice_count == cur_slice_count)
 		return result;
 

drivers/gpu/drm/amd/display/dc/dml/dcn32/dcn32_fpu.c

@@ -1177,6 +1177,9 @@ static void init_pipe_slice_table_from_context(
 		stream = context->streams[i];
 		otg_master = resource_get_otg_master_for_stream(
 				&context->res_ctx, stream);
+		if (!otg_master)
+			continue;
+
 		count = resource_get_odm_slice_count(otg_master);
 		update_slice_table_for_stream(table, stream, count);
 

drivers/gpu/drm/amd/display/dc/dml2/dml21/dml21_utils.c

@@ -120,6 +120,7 @@ int dml21_find_dc_pipes_for_plane(const struct dc *in_dc,
 	} else {
 		/* stream was configured with dummy plane, so get pipes from opp head */
 		struct pipe_ctx *otg_master_pipe = dml_ctx->config.callbacks.get_otg_master_for_stream(&context->res_ctx, dc_main_stream);
+		if (otg_master_pipe != NULL)
 			num_pipes = dml_ctx->config.callbacks.get_opp_heads_for_otg_master(otg_master_pipe, &context->res_ctx, dc_main_pipes);
 	}
 

drivers/gpu/drm/amd/display/dc/dml2/dml2_dc_resource_mgmt.c

@@ -905,6 +905,9 @@ static unsigned int get_source_odm_factor(const struct dml2_context *ctx,
 {
 	struct pipe_ctx *otg_master = ctx->config.callbacks.get_otg_master_for_stream(&state->res_ctx, stream);
 
+	if (!otg_master)
+		return 0;
+
 	return ctx->config.callbacks.get_odm_slice_count(otg_master);
 }