diff --git a/drivers/staging/comedi/drivers/quatech_daqp_cs.c b/drivers/staging/comedi/drivers/quatech_daqp_cs.c
index 0ea02f0e1aa2..b56d126869e3 100644
--- a/drivers/staging/comedi/drivers/quatech_daqp_cs.c
+++ b/drivers/staging/comedi/drivers/quatech_daqp_cs.c
@@ -394,6 +394,10 @@ static int daqp_ai_cmdtest(struct comedi_device *dev,
 
 	/* Step 2b : and mutually compatible */
 
+	/* the async command requires a pacer */
+	if (cmd->scan_begin_src != TRIG_TIMER && cmd->convert_src != TRIG_TIMER)
+		err |= -EINVAL;
+
 	if (err)
 		return 2;