drm/amd/display: drain dmub inbox if queue is full

[Why & How]
If dmub command queuing fails due to the inbox being full, flush the
inbox and resubmit the comamnd. This was previously the default behavior
but was lost in a refactor.
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Josip Pavic <Josip.Pavic@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/dc_dmub_srv.c

@@ -139,6 +139,15 @@ bool dc_dmub_srv_cmd_run_list(struct dc_dmub_srv *dc_dmub_srv, unsigned int coun
 		// Queue command
 		status = dmub_srv_cmd_queue(dmub, &cmd_list[i]);
 
+		if (status == DMUB_STATUS_QUEUE_FULL) {
+			/* Execute and wait for queue to become empty again. */
+			dmub_srv_cmd_execute(dmub);
+			dmub_srv_wait_for_idle(dmub, 100000);
+
+			/* Requeue the command. */
+			status = dmub_srv_cmd_queue(dmub, &cmd_list[i]);
+		}
+
 		if (status != DMUB_STATUS_OK) {
 			DC_ERROR("Error queueing DMUB command: status=%d\n", status);
 			dc_dmub_srv_log_diagnostic_data(dc_dmub_srv);