drm/amd/display: DCN2X Find Secondary Pipe properly in MPO + ODM Case

[WHY]
Previously as MPO + ODM Combine was not supported, finding secondary pipes
for each case was mutually exclusive. Now that both are supported at the same
time, both cases should be taken into account when finding a secondary pipe.

[HOW]
If a secondary pipe cannot be found based on previous bottom pipe,
search for a second pipe using next_odm_pipe instead.
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Sung Lee <sung.lee@amd.com>
Reviewed-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Acked-by: Anson Jacob <anson.jacob@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org # 5.10.x

drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c

@@ -2517,8 +2517,7 @@ struct pipe_ctx *dcn20_find_secondary_pipe(struct dc *dc,
 		 * if this primary pipe has a bottom pipe in prev. state
 		 * and if the bottom pipe is still available (which it should be),
 		 * pick that pipe as secondary
-		 * Same logic applies for ODM pipes. Since mpo is not allowed with odm
-		 * check in else case.
+		 * Same logic applies for ODM pipes
 		 */
 		if (dc->current_state->res_ctx.pipe_ctx[primary_pipe->pipe_idx].bottom_pipe) {
 			preferred_pipe_idx = dc->current_state->res_ctx.pipe_ctx[primary_pipe->pipe_idx].bottom_pipe->pipe_idx;
@@ -2526,7 +2525,9 @@ struct pipe_ctx *dcn20_find_secondary_pipe(struct dc *dc,
 				secondary_pipe = &res_ctx->pipe_ctx[preferred_pipe_idx];
 				secondary_pipe->pipe_idx = preferred_pipe_idx;
 			}
-		} else if (dc->current_state->res_ctx.pipe_ctx[primary_pipe->pipe_idx].next_odm_pipe) {
+		}
+		if (secondary_pipe == NULL &&
+				dc->current_state->res_ctx.pipe_ctx[primary_pipe->pipe_idx].next_odm_pipe) {
 			preferred_pipe_idx = dc->current_state->res_ctx.pipe_ctx[primary_pipe->pipe_idx].next_odm_pipe->pipe_idx;
 			if (res_ctx->pipe_ctx[preferred_pipe_idx].stream == NULL) {
 				secondary_pipe = &res_ctx->pipe_ctx[preferred_pipe_idx];