staging: comedi: pcl711: remove "empty acquisition" async command

This driver currently allows a cmd->stop_src == TRIG_COUNT with a cmd->stop_arg
of 0. This causes the (*do_cmd) to immediately generate a COMEDI_CB_EOA event
without acquiring any data.

This "empty acquisition" async command is not really useful. Validate that the
cmd->stop_arg is >= 1 in the (*do_cmdtest) and remove the "empty acquisition"
code.

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/pcl711.c b/drivers/staging/comedi/drivers/pcl711.c
index 20ed09c..47f4887 100644 (file)
--- a/drivers/staging/comedi/drivers/pcl711.c
+++ b/drivers/staging/comedi/drivers/pcl711.c
@@ -334,7 +334,9 @@ static int pcl711_ai_cmdtest(struct comedi_device *dev,
        err |= cfc_check_trigger_arg_is(&cmd->convert_arg, 0);
        err |= cfc_check_trigger_arg_is(&cmd->scan_end_arg, cmd->chanlist_len);
 
-       if (cmd->stop_src == TRIG_NONE)
+       if (cmd->stop_src == TRIG_COUNT)
+               err |= cfc_check_trigger_arg_min(&cmd->stop_arg, 1);
+       else    /* TRIG_NONE */
                err |= cfc_check_trigger_arg_is(&cmd->stop_arg, 0);
 
        if (err)
@@ -376,15 +378,8 @@ static int pcl711_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 
        pcl711_set_changain(dev, s, cmd->chanlist[0]);
 
-       if (cmd->stop_src == TRIG_COUNT) {
-               if (cmd->stop_arg == 0) {
-                       /* an empty acquisition */
-                       s->async->events |= COMEDI_CB_EOA;
-                       comedi_event(dev, s);
-                       return 0;
-               }
+       if (cmd->stop_src == TRIG_COUNT)
                devpriv->ntrig = cmd->stop_arg;
-       }
 
        if (cmd->scan_begin_src == TRIG_TIMER) {
                pcl711_ai_load_counters(dev);