staging: comedi: pcmuio: 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/pcmuio.c b/drivers/staging/comedi/drivers/pcmuio.c
index 3aedeca..eb60663 100644 (file)
--- a/drivers/staging/comedi/drivers/pcmuio.c
+++ b/drivers/staging/comedi/drivers/pcmuio.c
@@ -416,13 +416,6 @@ static int pcmuio_start_intr(struct comedi_device *dev,
        unsigned int pol_bits = 0;
        int i;
 
-       if (!chip->continuous && chip->stop_count == 0) {
-               /* An empty acquisition! */
-               s->async->events |= COMEDI_CB_EOA;
-               chip->active = 0;
-               return 1;
-       }
-
        chip->enabled_mask = 0;
        chip->active = 1;
        if (cmd->chanlist) {
@@ -564,16 +557,10 @@ static int pcmuio_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);
 
-       switch (cmd->stop_src) {
-       case TRIG_COUNT:
-               /* any count allowed */
-               break;
-       case 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);
-               break;
-       default:
-               break;
-       }
 
        if (err)
                return 3;