staging: comedi: addi_apci_3xxx: fix ai subdevice 'len_chanlist'

Due to a driver limitation, the (*do_cmdtest) for the analog input subdevice
overrides the cmd->chanlist_len to force single channel chanlists. But, the
cmd->scan_end_arg was already validated before this happens. Instead of
fixing the (*do_cmdtest) just set the subdevice len_chanlist to 1 to limit
the chanlist size. Move the comment also.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/comedi/drivers/addi_apci_3xxx.c b/drivers/staging/comedi/drivers/addi_apci_3xxx.c
index 6dc11c4..64c37b6 100644 (file)
--- a/drivers/staging/comedi/drivers/addi_apci_3xxx.c
+++ b/drivers/staging/comedi/drivers/addi_apci_3xxx.c
@@ -573,26 +573,6 @@ static int apci3xxx_ai_cmdtest(struct comedi_device *dev,
 
        /* step 4: fix up any arguments */
 
-       /*
-        * FIXME: The hardware supports multiple scan modes but the original
-        * addi-data driver only supported reading a single channel with
-        * interrupts. Need a proper datasheet to fix this.
-        *
-        * The following scan modes are supported by the hardware:
-        * 1) Single software scan
-        * 2) Single hardware triggered scan
-        * 3) Continuous software scan
-        * 4) Continuous software scan with timer delay
-        * 5) Continuous hardware triggered scan
-        * 6) Continuous hardware triggered scan with timer delay
-        *
-        * For now, limit the chanlist to a single channel.
-        */
-       if (cmd->chanlist_len > 1) {
-               cmd->chanlist_len = 1;
-               err |= -EINVAL;
-       }
-
        tmp = cmd->convert_arg;
        err |= apci3xxx_ai_ns_to_timer(dev, &cmd->convert_arg,
                                       cmd->flags & TRIG_ROUND_MASK);
@@ -842,12 +822,30 @@ static int apci3xxx_auto_attach(struct comedi_device *dev,
                s->subdev_flags = SDF_READABLE | board->ai_subdev_flags;
                s->n_chan       = board->ai_n_chan;
                s->maxdata      = board->ai_maxdata;
-               s->len_chanlist = s->n_chan;
                s->range_table  = &apci3xxx_ai_range;
                s->insn_read    = apci3xxx_ai_insn_read;
                if (dev->irq) {
+                       /*
+                        * FIXME: The hardware supports multiple scan modes
+                        * but the original addi-data driver only supported
+                        * reading a single channel with interrupts. Need a
+                        * proper datasheet to fix this.
+                        *
+                        * The following scan modes are supported by the
+                        * hardware:
+                        *   1) Single software scan
+                        *   2) Single hardware triggered scan
+                        *   3) Continuous software scan
+                        *   4) Continuous software scan with timer delay
+                        *   5) Continuous hardware triggered scan
+                        *   6) Continuous hardware triggered scan with timer
+                        *      delay
+                        *
+                        * For now, limit the chanlist to a single channel.
+                        */
                        dev->read_subdev = s;
                        s->subdev_flags |= SDF_CMD_READ;
+                       s->len_chanlist = 1;
                        s->do_cmdtest   = apci3xxx_ai_cmdtest;
                        s->do_cmd       = apci3xxx_ai_cmd;
                        s->cancel       = apci3xxx_ai_cancel;