return 0;
 }
 
-static int labpc_ai_chanlist_invalid(const struct comedi_device *dev,
-                                    const struct comedi_cmd *cmd,
-                                    enum scan_mode mode)
+static int labpc_ai_check_chanlist(struct comedi_device *dev,
+                                  struct comedi_subdevice *s,
+                                  struct comedi_cmd *cmd)
 {
-       int channel, range, aref, i;
-
-       if (cmd->chanlist == NULL)
-               return 0;
+       enum scan_mode mode = labpc_ai_scan_mode(cmd);
+       unsigned int chan0 = CR_CHAN(cmd->chanlist[0]);
+       unsigned int range0 = CR_RANGE(cmd->chanlist[0]);
+       unsigned int aref0 = CR_AREF(cmd->chanlist[0]);
+       int i;
 
        if (mode == MODE_SINGLE_CHAN)
                return 0;
 
-       if (mode == MODE_SINGLE_CHAN_INTERVAL) {
-               if (cmd->chanlist_len > 0xff) {
-                       comedi_error(dev,
-                                    "ni_labpc: chanlist too long for single channel interval mode\n");
-                       return 1;
-               }
-       }
-
-       channel = CR_CHAN(cmd->chanlist[0]);
-       range = CR_RANGE(cmd->chanlist[0]);
-       aref = CR_AREF(cmd->chanlist[0]);
-
        for (i = 0; i < cmd->chanlist_len; i++) {
+               unsigned int chan = CR_CHAN(cmd->chanlist[i]);
+               unsigned int range = CR_RANGE(cmd->chanlist[i]);
+               unsigned int aref = CR_AREF(cmd->chanlist[i]);
 
                switch (mode) {
+               case MODE_SINGLE_CHAN:
+                       break;
                case MODE_SINGLE_CHAN_INTERVAL:
-                       if (CR_CHAN(cmd->chanlist[i]) != channel) {
-                               comedi_error(dev,
-                                            "channel scanning order specified in chanlist is not supported by hardware.\n");
-                               return 1;
+                       if (chan != chan0) {
+                               dev_dbg(dev->class_dev,
+                                       "channel scanning order specified in chanlist is not supported by hardware\n");
+                               return -EINVAL;
                        }
                        break;
                case MODE_MULT_CHAN_UP:
-                       if (CR_CHAN(cmd->chanlist[i]) != i) {
-                               comedi_error(dev,
-                                            "channel scanning order specified in chanlist is not supported by hardware.\n");
-                               return 1;
+                       if (chan != i) {
+                               dev_dbg(dev->class_dev,
+                                       "channel scanning order specified in chanlist is not supported by hardware\n");
+                               return -EINVAL;
                        }
                        break;
                case MODE_MULT_CHAN_DOWN:
-                       if (CR_CHAN(cmd->chanlist[i]) !=
-                           cmd->chanlist_len - i - 1) {
-                               comedi_error(dev,
-                                            "channel scanning order specified in chanlist is not supported by hardware.\n");
-                               return 1;
+                       if (chan != (cmd->chanlist_len - i - 1)) {
+                               dev_dbg(dev->class_dev,
+                                       "channel scanning order specified in chanlist is not supported by hardware\n");
+                               return -EINVAL;
                        }
                        break;
-               default:
-                       dev_err(dev->class_dev,
-                               "ni_labpc: bug! in chanlist check\n");
-                       return 1;
-                       break;
                }
 
-               if (CR_RANGE(cmd->chanlist[i]) != range) {
-                       comedi_error(dev,
-                                    "entries in chanlist must all have the same range\n");
-                       return 1;
+               if (range != range0) {
+                       dev_dbg(dev->class_dev,
+                               "entries in chanlist must all have the same range\n");
+                       return -EINVAL;
                }
 
-               if (CR_AREF(cmd->chanlist[i]) != aref) {
-                       comedi_error(dev,
-                                    "entries in chanlist must all have the same reference\n");
-                       return 1;
+               if (aref != aref0) {
+                       dev_dbg(dev->class_dev,
+                               "entries in chanlist must all have the same reference\n");
+                       return -EINVAL;
                }
        }
 
        if (err)
                return 4;
 
-       if (labpc_ai_chanlist_invalid(dev, cmd, mode))
+       /* Step 5: check channel list if it exists */
+       if (cmd->chanlist && cmd->chanlist_len > 0)
+               err |= labpc_ai_check_chanlist(dev, s, cmd);
+
+       if (err)
                return 5;
 
        return 0;